Дослідження інфрачервоного спектра молекули Fe(II)-порфіну в різних спінових станах квантово-хімічним методом функціоналу густини
Квантово-хімічним методом теорії функціоналу густини розраховано інфрачервоний (ІЧ) спектр поглинання молекули Fe(ІІ)-порфіну для синглетного, триплетного та квінтетного спінових станів. Для оптимізації геометрії і розрахунку ІЧ спектра молекули використано необмежений за спіном функціонал UB3LYP у...
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Інститут молекулярної біології і генетики НАН України
2007
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Мінаєв, Б.П. Мінаєв, О.Б. Говорун, Д.М. 2019-06-20T04:20:18Z 2019-06-20T04:20:18Z 2007 Дослідження інфрачервоного спектра молекули Fe(II)-порфіну в різних спінових станах квантово-хімічним методом функціоналу густини / Б.П. Мінаєв, О.Б. Мінаєв, Д.М. Говорун // Біополімери і клітина. — 2007. — Т. 23, № 6. — С. 519-528. — Бібліогр.: 21 назв. — укр., англ. 0233-7657 DOI: http://dx.doi.org/10.7124/bc.000787 https://nasplib.isofts.kiev.ua/handle/123456789/157522 577.175.6:544.18:543.422 Квантово-хімічним методом теорії функціоналу густини розраховано інфрачервоний (ІЧ) спектр поглинання молекули Fe(ІІ)-порфіну для синглетного, триплетного та квінтетного спінових станів. Для оптимізації геометрії і розрахунку ІЧ спектра молекули використано необмежений за спіном функціонал UB3LYP у базисі 6-311G. Показано, що квінтетний стан 5В2g симетрії D₂h є основним. Для триплетного стану з низькою енергією ³A₂g і синглетного стану з високою енергією ¹A₁g , які мають симетрію D₄h, ІЧ спектри досліджено в точковій групі симетрії D₂h. Проаналізовано усі активні в ІЧ спектрі коливальні моди. У квінтетному стані низькочастотні неплощинні коливальні моди з великим зміщенням іона Fe(ІІ) мають різні інтенсивності і частотні зміщення порівняно з синглетним і триплетним станами. The infrared (IR) absorption spectra of the Fe(II) porphin molecule (Fe(II)P) are calculated by the quantum-chemical method of density functional theory (DFT) for the singlet, triplet, and quintet spin states. The UB3LYP functional with the 6-311G basis set is used in geometry optimization and IR calculations. The quintet state ⁵B₂g of the D₂h symmetry is found to be the ground state. Though the close-lying triplet ³A₂g and high-energy singlet ¹A₁g states belong to the D₄h symmetry, the IR spectra have been analyzed in terms of the lower symmetry D₂h point group. All IR active vibrations are tabulated and discussed. The low-frequency modes with large out-of-plane displacements of Fe(II) ion have different IR intensities, normal vibrations, and frequency shifts in the quintet state in respect to the singlet and triplet states. Квантово-химическим методом теории функционала плотности рассчитаны инфракрасные (ИК) спектры поглощения молекулы Fe(II)-порфина для синглетного, триплетного и квинтетного спиновых состояний. Для оптимизации геометрии и расчета ИК спектра использован неограниченный по спину функционал UB3LYP в базисе 6-311G. Показано, что квинтетное состояние ⁵B₂g симметрии D₂h является основным. Для триплетного состояния с низкой энергией ³A₂g и синглетного состояния с высокой энергией ¹A₁g, имеющих симметрию D₄h, ИК спектры изучены в точечной группе симметрии D₂h. Проанализированы все активные в ИК спектре колебательные моды. В квинтетном состоянии низкочастотные внеплоскостные колебательные моды с большим смещением иона Fe(II) имеют различные интенсивности и частотные сдвиги по сравнению с синглетным и триплетным состояниями. uk Інститут молекулярної біології і генетики НАН України Біополімери і клітина Молекулярна біофізика Дослідження інфрачервоного спектра молекули Fe(II)-порфіну в різних спінових станах квантово-хімічним методом функціоналу густини Исследование инфракрасного спектра молекулы Fe(II)-порфина в разных спиновых состояниях квантово-химическим методом функционала плотности Investigation of infrared spectrum of Fe(II) porphin in different spin states by quantum chemical density functional theory Article published earlier |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| title |
Дослідження інфрачервоного спектра молекули Fe(II)-порфіну в різних спінових станах квантово-хімічним методом функціоналу густини |
| spellingShingle |
Дослідження інфрачервоного спектра молекули Fe(II)-порфіну в різних спінових станах квантово-хімічним методом функціоналу густини Мінаєв, Б.П. Мінаєв, О.Б. Говорун, Д.М. Молекулярна біофізика |
| title_short |
Дослідження інфрачервоного спектра молекули Fe(II)-порфіну в різних спінових станах квантово-хімічним методом функціоналу густини |
| title_full |
Дослідження інфрачервоного спектра молекули Fe(II)-порфіну в різних спінових станах квантово-хімічним методом функціоналу густини |
| title_fullStr |
Дослідження інфрачервоного спектра молекули Fe(II)-порфіну в різних спінових станах квантово-хімічним методом функціоналу густини |
| title_full_unstemmed |
Дослідження інфрачервоного спектра молекули Fe(II)-порфіну в різних спінових станах квантово-хімічним методом функціоналу густини |
| title_sort |
дослідження інфрачервоного спектра молекули fe(ii)-порфіну в різних спінових станах квантово-хімічним методом функціоналу густини |
| author |
Мінаєв, Б.П. Мінаєв, О.Б. Говорун, Д.М. |
| author_facet |
Мінаєв, Б.П. Мінаєв, О.Б. Говорун, Д.М. |
| topic |
Молекулярна біофізика |
| topic_facet |
Молекулярна біофізика |
| publishDate |
2007 |
| language |
Ukrainian |
| container_title |
Біополімери і клітина |
| publisher |
Інститут молекулярної біології і генетики НАН України |
| format |
Article |
| title_alt |
Исследование инфракрасного спектра молекулы Fe(II)-порфина в разных спиновых состояниях квантово-химическим методом функционала плотности Investigation of infrared spectrum of Fe(II) porphin in different spin states by quantum chemical density functional theory |
| description |
Квантово-хімічним методом теорії функціоналу густини розраховано інфрачервоний (ІЧ) спектр поглинання молекули Fe(ІІ)-порфіну для синглетного, триплетного та квінтетного спінових станів. Для оптимізації геометрії і розрахунку ІЧ спектра молекули використано необмежений за спіном функціонал UB3LYP у базисі 6-311G. Показано, що квінтетний стан 5В2g симетрії D₂h є основним. Для триплетного стану з низькою енергією ³A₂g і синглетного стану з високою енергією ¹A₁g , які мають симетрію D₄h, ІЧ спектри досліджено в точковій групі симетрії D₂h. Проаналізовано усі активні в ІЧ спектрі коливальні моди. У квінтетному стані низькочастотні неплощинні коливальні моди з великим зміщенням іона Fe(ІІ) мають різні інтенсивності і частотні зміщення порівняно з синглетним і триплетним станами.
The infrared (IR) absorption spectra of the Fe(II) porphin molecule (Fe(II)P) are calculated by the quantum-chemical method of density functional theory (DFT) for the singlet, triplet, and quintet spin states. The UB3LYP functional with the 6-311G basis set is used in geometry optimization and IR calculations. The quintet state ⁵B₂g of the D₂h symmetry is found to be the ground state. Though the close-lying triplet ³A₂g and high-energy singlet ¹A₁g states belong to the D₄h symmetry, the IR spectra have been analyzed in terms of the lower symmetry D₂h point group. All IR active vibrations are tabulated and discussed. The low-frequency modes with large out-of-plane displacements of Fe(II) ion have different IR intensities, normal vibrations, and frequency shifts in the quintet state in respect to the singlet and triplet states.
Квантово-химическим методом теории функционала плотности рассчитаны инфракрасные (ИК) спектры поглощения молекулы Fe(II)-порфина для синглетного, триплетного и квинтетного спиновых состояний. Для оптимизации геометрии и расчета ИК спектра использован неограниченный по спину функционал UB3LYP в базисе 6-311G. Показано, что квинтетное состояние ⁵B₂g симметрии D₂h является основным. Для триплетного состояния с низкой энергией ³A₂g и синглетного состояния с высокой энергией ¹A₁g, имеющих симметрию D₄h, ИК спектры изучены в точечной группе симметрии D₂h. Проанализированы все активные в ИК спектре колебательные моды. В квинтетном состоянии низкочастотные внеплоскостные колебательные моды с большим смещением иона Fe(II) имеют различные интенсивности и частотные сдвиги по сравнению с синглетным и триплетным состояниями.
|
| issn |
0233-7657 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/157522 |
| citation_txt |
Дослідження інфрачервоного спектра молекули Fe(II)-порфіну в різних спінових станах квантово-хімічним методом функціоналу густини / Б.П. Мінаєв, О.Б. Мінаєв, Д.М. Говорун // Біополімери і клітина. — 2007. — Т. 23, № 6. — С. 519-528. — Бібліогр.: 21 назв. — укр., англ. |
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MOLECULAR BIOPHYSICS
In ves ti ga tion of in fra red spec trum of Fe(II) porphin in
dif fer ent spin states by quan tum chem i cal den sity
func tional theory
B. F. Minaev, A. B. Minaev, D. N. Hovorun1
Cherkassy state technologikal uni ver sity
Shevchenko blvd, 460, Cherkassy,18006, Ukraine
1In sti tute of mo lec u lar bi ol ogy and ge net ics NAS of Ukraine
Academicain Zabolotnog str., 150, Kyiv, 03680 Ukraine
bfmin@ram bler.ru
The in fra red (IR) ab sorp tion spec tra of the Fe(II) porphin mol e cule (Fe(²²)P) are cal cu lated by the quan -
tum-chem i cal method of den sity func tional the ory (DFT) for the sin glet, trip let, and quin tet spin states. The
UB3LYP func tional with the 6-311G ba sis set is used in ge om e try op ti mi za tion and IR cal cu la tions. The
quin tet state 5B
2g
of the D
2h
sym me try is found to be the ground state. Though the close-ly ing trip let 3À
2g
and
high-en ergy sin glet 1À
1g
states be long to the D
4h
sym me try, the IR spec tra have been an a lyzed in terms of the
lower sym me try D
2h
point group. All IR ac tive vi bra tions are tab u lated and dis cussed. The low-fre quency
modes with large out-of-plane dis place ments of Fe(II) ion have dif fer ent IR in ten si ties, nor mal vi bra tions,
and fre quency shifts in the quin tet state in re spect to the sin glet and trip let states.
Keywords: Fe(II) porphin, sin glet, trip let, quin tet, spin states, den sity func tional the ory, IR ab sorp tion
spec trum, low-fre quency modes
In tro duc tion. The change of spin state of ac tive Fe(II)
cen tre of hemoproteins is a spe cific fea ture of a num ber
of en zy matic re ac tions (e.g. re ac tion which takes place
in cytochrome at cam phor hydroxylation) [1, 2]. The
tran si tion from low- to high-spin state (S = 2, where S is
com plete spin of mol e cule) dur ing bind ing of hy dro -
pho bic sub strates has a sig nif i cant in flu ence on re dox
equi lib rium and en zy matic cy cle in gen eral [1]. The o -
ret i cal in ves ti ga tions of these pro cesses us ing the den -
sity func tional the ory (DFT) meth ods [3] have be come
of ma jor im por tance in bio chem is try of hemoproteins
in re cent years as they sup ply the unique in for ma tion
on spin role in me tab o lism [4–7]. The re la tion be tween
en ergy and spin of hemoprotein in the frame work of
DFT method re vealed it to be de ter mined by dif fer ent
fac tors such as DFT func tional, char ac ter of ex change
ef fects, ba sis set of atomic orbitals (AO), etc [8–10],
thus, the need for op ti mal DFT method, which will al -
low de fin ing cor rect se quence of spin multiplets in the
sim plest heme Fe(II)-porphin (Fe(II)P) model, and de -
scrib ing ba sic phys i cal-chem i cal pa ram e ters of mol e -
cule and the de pend ence of these pa ram e ters on elec -
tronic spin within this ap proach, is the im por tant is sue
of today.
In Ref. [11] the cor rect se quence of Fe(II)P spin
states, match ing the re sults of the most ac cu rate cal cu -
la tions based on the method of con fig u ra tion in ter ac -
tion (CI) [12], was ob tained on the ba sis of DFT study.
Op ti mised en er gies of the sym met ri cal 1A1g and 3A2g
states of D4h group were shown to be higher than the en -
ergy of the quin tet state 5B2g, which cor re sponds to D2h
sym me try group.
519
ISSN 0233-7657. Biopolymers and cell. 2007. vol. 23. N 6. Translated from Ukrainian.
Ó B. F. MINAEV, A. B. MINAEV, D. N. HOVORUN, 2007
The con nec tion be tween Fe(II)P spin and the force
field of all at oms of the mol e cule re quires ap pro pri ate
de scrip tion, as fre quency of vi bra tions pro vide not only
the way to ex per i men tal val i da tion us ing IR and Raman
spec tra, but also de ter mine the re ac tiv ity of
hemoproteins dur ing their in ter ac tion with lig ands.
Cur rent work pres ents the in ves ti ga tion of the IR
spec trum of Fe(II)P in dif fer ent spin states (sin glet (S),
trip let (T), quin tet (Q)) us ing the DFT method. Spe cial
em pha sis is put on the anal y sis of forms of vi bra tion
modes with high dis place ment am pli tude of the Fe(II)
ion, as this shift is known to be the cen tral as pect of
func tion ally im por tant dy nam ics of hemoproteins.
Ma te ri als and Meth ods. The meth ods, pre vi ously
used for solv ing the prob lem of vi bra tions, are based on
em piric se lec tion of force field for the known va lence
vi bra tions of pyrrol rings [13–15]. At the same time the
out-of-place vi bra tions were not in ves ti gated at all, as it
is ex tremely hard to de ter mine cor re spond ing force
con stants for the whole porphin macrocycle. Quan -
tum-chem i cal meth ods of DFT, based on the ap pli ca -
tion of elec tronic den sity func tional for eval u a tion of
en ergy, and, con se quently, force con stants, al lowed
cal cu lat ing IR and Raman spec tra of many porphins on
the ba sis of one the o ret i cal ap proach [8, 10, 16–18]. To
cal cu late equi lib rium ge om e try, elec tronic struc ture,
and IR spec trum of Fe(II)P mol e cule we used method
of DFT at the B3LYP level of the ory with ex tended
AO-ba sis set (6-311G) [3].
Com plete op ti mi sa tion of ge om e try was per formed
for all spin states of FeP. The Hessian ma trixes were
cal cu lated and all real fre quen cies of nor mal vi bra tions
were ob tained for all sta tion ary points. In ten sity of IR
spec tra was cal cu lated us ing de riv a tives of mo lec u lar
di pole mo ment. All cal cu la tions were per formed us ing
GAUSSI AN-03 soft ware [19] in Lab o ra tory of The o -
ret i cal Chem is try of Stock holm Cen ter for Phys ics, As -
tron omy, and Bio tech nol ogy (SCFAB).
Re li able ex per i men tal Fe(II)P IR spec tra are not
pres ent in lit er a ture due to fast ox i da tion of Fe(II)P to
Fe(III)P. More over, the prep a ra tion of crys tal sam ples
in cludes the ap pear ance of com plexes of dif fer ent spin
states [19], thus the re sults of our work were com pared
to the re sults of cal cu la tion of porphin mol e cule (H2P)
in the same and in ap prox i mate 6-31G** bases [10],
and with the re sults of cal cu la tion of mag ne -
sium-porphin (MgP) and zinc-porphin (ZnP) com -
plexes in B3LYP/6-31G* method, which are spe cific
for the pres ence of re li able ex per i men tal data on vi bra -
tions in IR spec tra [10]. Com par a tive anal y sis al lowed
eval u at ing the val ues of zoom mul ti pli ers, which
amount to 0.97 for va lence vi bra tions of C–N, C–C
bonds and to 0.96 for C–H bonds, while for va lence vi -
bra tions of Fe–N bonds with sig nif i cant dis place ment
of Fe(II) ions it amounts to 0.98, for fre quen cies of
deformational out-of-plane vi bra tions with out dis -
place ments of Fe(II) ions it is equal to 0.975.
Un for tu nately, ex per i men tal data for low-fre -
quency vi bra tions (n » 400 cm–1) in IR spec tra of metal
com plexes MgP and ZnP are not known, there fore,
zoom mul ti plier of this part of spec trum was not eval u -
ated.
Re sults and Dis cus sion. Nu mer a tion of at oms and
se lec tion of axes in Fe(II)P mol e cule are pre sented in
Fig.1. Tra di tional mark ing sys tem [13] was used for re -
view ing ge om e try and elec tronic struc ture of the mol e -
cule, i.e. the car bon at oms in a-po si tions – Ca, in b-po -
si tions – Cb, in meso po si tion of macrocycle (meth ane
MINAEV B. F., MINAEV A. B., HOVORUN D. N.
520
Fig.1 Mark ing of at oms and se lec tion of axes in Fe(II)P mol e cule
bridges) – Cm. Pyrrol rings are marked by Ro man nu -
mer als I–IV, po si tion of bridge car bonic at oms (meso
po si tion) are marked by Greek let ters a, b, g, d. At oms
of pyrrol rings with N35 and N36 num bers are marked by
ac cent (Ca¢, Cb¢) in or der to avoid am bi gu ity while com -
par ing sin glet and trip let elec tronic states of Fe(II)P
mol e cule, be long ing to the point groups of sym me try
D4h, with the quin tet state (D2h group).
Tak ing into ac count the data in Ta ble 1, which pres -
ents the cor re la tions of sym me try of vi bra tion modes in
the point groups D4h and D2h, the nor mal vi bra tions of
Fe(II)P mol e cule in sin glet and trip let states in group
D4h are clas si fied ac cord ing to the type of sym me try, i.e.
6 a2u, 4 b2u, 3 a1u, 5 b1u, 16 eg – out-of-plane vi bra tions;
36 eu, 9 a1g, 9 b1g, 9 b2g, 8 a2g – in-plane vi bra tions.
l Vi bra tions of the b1u, b2u, and b3u sym me try in the
point group D2h are spe cific to IR spec trum, while vi bra -
tions ag, b1g, b2g, b3g are ac tive in Raman spec tra and
vibronic spec tra. Group D4h is spe cific for al lowed vi -
bra tions of a2u, e2u, while vi bra tions of b2u type are for -
bid den in IR spec tra, due to the fact that the point group
D2h is only a D4h sub-group. Thus in the IR spec tra of
Fe(II)P in sin glet and trip let states the num ber of al -
lowed vi bra tions of out-of-plane vi bra tional modes is
de creased by 4.
The cal cu la tions of vi bra tional fre quen cies and nor -
mal modes of Fe(II)P mol e cule in dif fer ent spin elec -
tronic states (1Ag,
3B1g,
5B2g) re vealed the pres ence of
only five vi bra tional modes with large Fe(II) ion dis -
place ments, three of which are out-of-plane dis place -
ments. Dis place ments of Fe(II) ion (a.u.) along Oz axis
which fit into in her ent vec tor lay out for nor mal vi bra -
tions are pre sented in Ta ble 2. One more vi bra tional
mode (11) with large dis place ment of Fe(II) ion (–0.15
a.u.) is ob tained in the quin tet state, whereas in sin glet
and trip let states in this vi bra tional mode the dis place -
ment of Fe(II) ion has not been ob served.
The range of 0–426 cm–1 is spe cific for out-of-plane
nor mal vi bra tions with large dis place ments of Fe(II)
ion along Oz axis and low-in ten sity de gen er ate skel e tal
plane vi bra tions, in volv ing Fe–N bonds with dif fer ent
dis place ments of Fe(II) ion (Ta ble 2, 3), as well as for
swing ing of the porphin skel e ton, pul sa tion, and twist -
ing of pyrrol rings (Ta ble 3 pres ents all cal cu lated fre -
quen cies of nor mal vi bra tions re gard less of zoom mul -
ti plier).
Out-of-plane vi bra tion mode 2 and the mode 1 in S
and T states are pro hib ited by sym me try for IR ab sorp -
tion of quanta, in quin tet state mode 1 is al lowed in IR
spec trum, yet is spe cific for rather low in ten sity (I =
0.0002 km/mole), there fore, in IR spec trum of Fe(II)P
the mode 3 was shown to be of the low est fre quency.
The cal cu lated fre quen cies are equal to 110, 106, and
78 cm–1 in the sin glet, trip let, and quin tet states, re spec -
tively. This mode was ob served to have the swing ing of
pyrrol rings dur ing the atomic mo tion of Fe and N up -
wards from the mo lec u lar plane, with the move ment
side ways and back, i.e. ei ther the crown was formed
IN VES TI GA TION OF IN FRA RED SPEC TRUM OF Fe(II) PORPHIN
521
Plane vibrations Out-of-plane vibrations
D4h D2h D4h D2h
eu b2u eg b2g
eu b3u eg b3g
a1g ag a2u b1u
b1g ag b2u b1u
a2g b1g a1u au
b2g b1g b1u au
Ta ble 1
Sym me try cor re la tion of vi bra tion modes of Fe(II)P
mol e cule in the point groups D4h and D2h
Electronic state of molecule (in D2h)
1Ag
3B1g
5B2g
Mode
Displac
ement
Mode
Displac
ement
Mode
Displac
ement
Out-of-plane vibrations
2 0 2 0 1 –0.01
3 –0.20 3 –0.21 3 –0.24
13 0 11 0 11 –0.15
14 –0.15 12 –0.17 7 –0.17
18 –0.15 18 –0.13 17 –0.04
33 –0.02 33 –0.02 33 –0.01
Ta ble 2
Dis place ment of the Fe(II) ion (a.u.) in nor mal vi bra -
tions of Fe(II)P in dif fer ent spin states, cal cu lated by
the B3LYP/6-311G method
522
MINAEV B. F., MINAEV A. B., HOVORUN D. N.
Ta ble 3
Fre quen cies (n, cm–1) and in ten sity (I, km/mole) of nor mal vi bra tions in IR spec trum of Fe(II)-porphin ab sorp tion in the sin glet, trip let
and quin tet spin states, cal cu lated by the of B3LYP/6-311G method .
Sym
metry
(D2h)
Type of vibration
Electronic state of molecule(D2h symmetry)
1Ag
3B1g
5B2g
Mode n I Mode n I Mode n I
1 2 3 4 5 6 7 8 9 10 11
b1u
Out-of-plane. upwards: Ca¢ N
33, 34, g(CbH); downwards:
Ña¢, N
35, 36, g(Cb¢H)
2 41 0 2 44 0 1 58 2´10-4
b1u
Out-of-plane. upwards: g(CbH), g(Cb¢H), g(CmH);
downwards: Fe, N33 - 36 3 110 7,9 3 106 4,6 3 78 1,6
b3u
nas(N
35–Fe and N36–Fe) with large displacement of Fe
atom + displacement of rings I and III + pulsation of
rings II and IV + d(ÐCa¢ NCa¢, Cb¢ Ca¢ Cm)
11 275 0.07 13 304 0.6 13 267 0.03
b2u
nas(N
33–Fe and N34–Fe) with large displacement of Fe
atom + displacement of rings II and IV + pulsation of
rings I and III + d(ÐCaNCa, CbCaCm)
12 275 0.07 14 304 0.6 12 263 0.7
b1u
Out-of-plane. upwards: Ña¢, N
35, 36, g(CbH);
downwards: Ca, N33, 34, g(Cb¢H), Fe
13 284 0 11 286 0 11 251 12.4
b1u
Out-of-plane. upwards: Ca, Ca¢, N
33–36, g(CmH);
downwards: Fe, g(CbH), g(Cb¢H)
14 294 0.8 12 290 5.9 7 208 26.0
b3u
nas(N
35–Fe and N36–Fe) displacement of rings II and IV
along Îx + sym. twisting of rings I and III +
d(ÐCaNFe, Ca¢NCa¢, CmCaN, CmCa¢N)
15 349 1,5 16 368 0.4 16 355 5.8
b2u
nas(N
33–Fe and N34–Fe) displacement of rings I and III
along Oy + sym. twisting of rings II and IV+
d(ÐCa¢NFe, CaNCa, CmCaN, CmCa¢N)
16 349 1,5 15 368 0.4 15 353 4,6
b1u
Out-of-plane. upwards: Ca, Ca¢, N
33–36, g(CbH), g(Cb¢H);
downwards: Fe, g(CmH)
18 400 24.4 18 385 36.2 17 358 23.4
b3u
nas(N
35–Fe and N36–Fe) with large displacement of Fe
atom + swinging of skeleton along Îx + d(ÐCbCaCm,
CaCmCa¢)
19 421 11.4 19 426 10,2 20 409 7.2
b2u
nas(N
33–Fe and N34–Fe) with large displacement of Fe
atom + swinging of skeleton along Îy + d(ÐCb¢ Ca¢ Cm,
CaCmCa¢)
20 421 11.4 20 426 10.2 19 405 11.6
b1u
Out-of-plane. upwards: Ca¢, N
33, 34, H at Cb;
downwards: Ca, N35, 36, H at Cb¢
27 654 0 29 674 0 29 684 0.2
b1u
Out-of-plane. upwards: N33 - 36, H at Cb and Cb¢;
g(CmH); downwards: Ca, Ca¢, Fe
33 723 34.9 33 727 31.2 33 729 22.3
b3u
nas(N
35–Fe and N36–Fe) + ns(Ca¢ –N), ns(Ca¢ –Cb¢) –
pulsation of rings II and IV in antiphase + twisting of
rings I and III + r(rCmH) + d(ÐCa¢NCa¢, CaCmCa¢ ,
CmCaN, CmCa¢N)
36 759 12.1 36 761 14.7 37 759 18.8
b2u
nas(N
33–Fe and N34–Fe) + ns(Ca–N), ns(Ca–Cb) –
pulsation of rings I and III in antiphase + twisting of
rings II and IV + r(rCmH) + d(ÐCaNCa, CaCmCa¢,
CmCaN, CmCa¢N)
37 759 12.1 37 761 14.7 35 756 18.2
523
IN VES TI GA TION OF IN FRA RED SPEC TRUM OF Fe(II) PORPHIN
1 2 3 4 5 6 7 8 9 10 11
b1u
Out-of-plane. upwards: H at Cb and Cb¢; Ca, Ca¢, Cm;
downwards: Cb, Cb¢, m-Í, N33 – 36 38 790 94.0 38 791 98.2 38 792 103.0
b1u
Out-of-plane. upwards: H at Cb¢ ; Ca, Cb¢, N
35, 36;
downwards: H at Cb¢ ; Cb, Ca¢, N
33, 34 41 805 0 41 808 0 41 814 0.4
b2u
nas(N
33–Fe and N34–Fe) + d(ÐÑa¢ Ñb¢ Ñb¢) – deformation
of rings II and IV + d(Ñb¢Í) + ns(Ca–N), ns(Ca–Cb) –
pulsation of rings I and III in antiphase + d(ÐÑaÑmÑa¢)
+ r(rCmH)
42 833 7.5 42 833 6.9 42 821 6.4
b3u
nas(N
35–Fe and N36–Fe) + d(ÐÑaÑbÑb) – deformation
of rings I and I²²+ d(ÑbÍ) + ns(Ca¢ –N), ns(Ca¢ –Cb¢) –
pulsation of rings I² and IV in antiphase +
d(ÐÑaÑmÑa¢) + r(rCmH)
43 833 7.5 43 833 6.9 44 826 3.9
b1u
Out-of-plane. upwards: H at Ñm, Cb and Cb¢ ; Ca, Ca¢,;
downwards: Cb, Cb¢, Cm
49 902 156.8 49 904 155.1 49 906 163.6
b2u
nas(Ca¢ –N) – in one phase + nas(Ca¢ –Ñb¢) – in one
phase in rings ²² and IV, twisting of these rings +
ns(Ca–Ñb) – pulsation of rings ² and III in antiphase +
nas(N
33–Fe and N34–Fe) + d(Ñb¢Í) + d(ÑbÍ)
55 1009 40.5 55 1013 63.9 58 1017 54.7
b3u
nas(Ca–N) – in one phase + nas(Ca–Ñb) – in one phase
in rings ² and I²², twisting of these rings + ns(Ca¢ –Ñb¢)
– pulsation of rings ²I and IV in antiphase +
nas(N35–Fe and N36–Fe) +d(Ñb¢Í) + d(ÑbÍ)
56 1009 40.5 56 1013 63.9 54 1007 78.7
b2u
ns(Ca–N) – in antiphase in rings ² and I²², pulsation of
rings + nas(Ca¢ –Ñb¢) – in one phase in rings ²² and IV,
twisting of these rings + nas(N
33–Fe and N34–Fe) +
d(Ñb¢Í) + d(ÑbÍ) + d(ÐCa¢ Cb¢ Cb¢, CCb¢H)
59 1015 28.2 59 1037 2.3 60 1027 28.5
b3u
ns(Ca¢ –N) – in antiphase in rings ²² and IV, pulsation
of these rings + nas(Ca–Ñb) – in one phase in rings ²
and III, twisting of these rings + nas(N
35–Fe and
N36–Fe) + d(Ñb¢Í) + d(ÑbÍ) + d(ÐCaCbCb, CCbH)
60 1015 28.2 60 1037 2.3 61 1037 3.2
b3u
d(Ñb¢Í) + d(ÐCCb¢H) + nas(Cb¢ –Ñb¢) + ns(Ca¢ –N) – in
antiphase in rings ²² and IV + nas(Ca–Ñb) – in one
phase in rings ² and III
63 1106 67.4 63 1105 69.3 63 1101 65.7
b2u
d(ÑbÍ) + d(ÐCCbH) + nas(Cb–Ñb) + ns(Ca–N) – in
antiphase in rings ² and III + nas(Ca¢ –Ñb¢) – in one
phase in rings ²² and IV
64 1106 67.4 64 1105 69.3 62 1096 58.9
b3u
nas(Ca–N) – in one phase in rings ² and I²², twisting of
these rings + d(ÐÑÑbÍ) + ns(Ca¢ –Ñb¢), ns(Ca¢ –N) – in
antiphase in rings ²² and IV, pulsation of these rings +
d(ÐÑÑmÍ) + nas(N
35–Fe and N36–Fe), no Fe atom
displacement
67 1170 7.2 67 1176 8.0 68 1181 12.1
b2u
nas(Ca¢ –N) – in one phase in rings ²I and IV, twisting
of these rings + d(ÐÑÑb¢Í) + ns(Ca–Ñb), ns(Ca–N) – in
antiphase in rings ² and III, pulsation of these rings +
d(ÑmÍ) + nas(N
33–Fe and N34–Fe), no Fe atom
displacement
68 1170 7.2 68 1176 8.0 66 1172 16.1
b2u
d(ÑmÍ) + d(ÐÑÑmÍ) + nas(Ca¢ –N) – in one phase in
rings ²I and IV, twisting of these rings + d(Ñb¢Í) +
d(ÐÑÑb¢Í) + nas(N
33–Fe and N34–Fe), ns(Ca–Ñb) – in
antiphase in rings ² and III, deformation of these rings
71 1277 6.4 71 1285 5.8 71 1264 0.007
524
MINAEV B. F., MINAEV A. B., HOVORUN D. N.
(Fig.2) or the mol e cule was ab sorbed. This vi bra tion
mode at tracts spe cial at ten tion due to its low-fre quency
na ture (Ta ble 3) and due to the most sig nif i cant dis -
place ments of Fe(II) ion (0.24 a.u.) dur ing the
1 2 3 4 5 6 7 8 9 10 11
b3u
d(ÑmÍ) + d(ÐÑÑmÍ) + nas(Ca–N) – in one phase in
rings ² and I²², twisting of these rings + d(ÑbÍ) +
d(ÑÑbÍ) + nas(N
35–Fe and N36–Fe), ns(Ca¢ –Ñb¢) – in
antiphase in rings ²² and IV, deformation of these rings
72 1277 6.4 72 1285 5.8 72 1275 0.55
b2u
nas(Ca¢ –N) – in one phase in rings ²I and IV + d(Ñb¢Í)
+ d(ÐÑÑb¢Í) + pulsation of rings ² and III, in
antiphase + n(Ca¢ –Ñm) + d(ÐÑÑmÍ)
73 1350 17.5 73 1349 17.9 73 1329 7.8
b3u
nas(Ca–N) – in one phase in rings ² and I²² + d(ÑbÍ) +
d(ÐÑÑbÍ) + pulsation of rings ²I and IV, in antiphase
+ n(Ca –Ñm) + d(ÐÑÑmÍ)
74 1350 17.5 74 1349 17.9 74 1334 14.3
b3u
ns(Ca¢ –N) – in antiphase in rings ²I and IV + nas(Ca
–N) – in one phase in rings ² and I²², twisting of these
rings + d(ÑbÍ) + d(ÐÑÑbÍ) + d(ÑmÍ) + d(ÐÑÑmÍ)
79 1411 1.8 79 1417 3.5 81 1421 5.7
b2u
ns(Ca–N) – in antiphase in rings ² and III + nas(Ca¢ –N)
– in one phase in rings ²I and IV, twisting of these
rings + d(Ñb¢ Í) + d(ÐÑÑb¢ Í) +d(ÑmÍ) + d(ÐÑÑmÍ)
80 1411 1.8 80 1417 3.5 79 1411 6.0
b3u
nas(Ca–Ñb) – in one phase in rings I and III, twisting of
these rings + nas(Ñb¢ –Ñb¢) + nas(Ca–N) + pulsation of
rings ²² and IV + d(ÑbÍ)+ d(ÐÑÑbÍ) + ns(C–Ñm)
83 1496 8.9 83 1496 10.3 84 1473 4.4
b2u
nas(Ca¢ –Ñb¢) – in one phase in rings ²² and IV, twisting
of these rings + nas(Ñb–Ñb) + nas(Ca¢ –N) + pulsation of
rings ² and I²² + d(Ñb¢ Í) + d(ÐÑÑb¢ Í) + ns(C–Ñm)
84 1496 8.9 84 1496 10.3 83 1460 1.8
b3u
nas(Ñb¢ –Ñb¢) + ns(Ca¢ –N) – in antiphase in rings ²² and ²V
+ nas(Ca–N) – in one phase in rings ² and III + ns(C–Ñm)
+ d(Ñb¢ Í) + d(ÐÑÑb¢ Í) +d(ÑbÍ) + d(ÐÑÑbÍ)
87 1581 23.0 87 1578 17.6 88 1558 24.5
b2u
nas(Ñb–Ñb) + ns(Ca–N) – in antiphase in rings ² and ²II
+ nas(Ca¢ –N) – in one phase in rings ²I and IV +
ns(C–Ñm) + d(Ñb¢Í) + d(ÐÑÑb¢ Í)+ d(ÑbÍ)+
d(ÐÑÑbÍ)
88 1581 23.0 88 1578 17.6 87 1545 7.0
b3u
nas(C–Ñm) + nas(Ñb¢ –Ñb¢) + nas(Ña–Ñb) – in one phase
in rings ² and ²II + nas(Ca–N) + nas(Ca¢ –N) + d(ÑmÍ) +
d(ÐÑÑmÍ)
90 1642 0.4 90 1634 0.06 91 1598 2.2
b2u
nas(C–Ñm) + nas(Ñb–Ñb) + nas(Ña¢ –Ñb¢) in one phase in
rings ²² and ²V + nas(Ca–N) + nas(Ca¢ –N) + d(ÑmÍ) +
d(ÐÑÑmÍ)
91 1642 0.4 91 1634 0.06 90 1586 6.9
b3u
n(Cm
a–Í) ³ (Cm
b–Í) – in one phase, but in antiphase
with n(Cmg–Í) and (Cmd–Í)
95 3191 14.3 95 3185 14.3 95 3173 23.0
b2u
n(Cm
a–Í) ³ (Cm
d–Í)) – in one phase, but in antiphase
with í(Cmb–Í) and (Cmg–Í)
96 3191 14.3 965 3185 14.3 96 3173 21.8
b3u nas(Cb–Í)(²), nas(Cb–Í)(²²²) – in one phase 99 3230 5.6 100 3227 6.6 101 3223.3 8.5
b2u nas(Cb¢ –Í)(²²), nas(Cb¢ –Í)(²V) – in one phase 100 3230 5.6 99 3227 6.6 99 3222.7 7.0
b3u ns(Cb¢ –Í)(²²), ns(Cb¢ –Í)(²V) – in antiphase 103 3253 36.0 103 3251 42.1 104 3246.1 53.2
b2u ns(Cb–Í)(²), ns(Cb–Í)(²²²) – in antiphase 104 3253 36.0 104 3251 42.1 103 3246.0 51.5
out-of-plane vi bra tions (Ta ble 2). This vi bra tion is ca -
pa ble to in duce the spin tran si tion with spin re verse in
re ac tions of hemoproteins and cytochromes [5]. Cal cu -
lated fre quency of the high-spin 5B2g state (78 cm–1) is
close to the value, ob served dur ing re ac tion dy nam ics
of myoglobin hemoprotein, i.e. 75 cm–1 [21]. No ta bly,
this form of vi bra tion is slightly dif fer ent from that cal -
cu lated in Ref. [8].
Vi bra tion mode 14 of the sin glet state (mode 12 in T
and mode 7 in Q state) was spe cific for the move ment
of pyrrol rings along with the move ment of Fe(II) ion
per pen dic u larly to the plane of the mol e cule, which re -
sulted in gen eral swing ing of porphin skel e ton.
It has to be noted that in Q state the am pli tude of vi -
bra tions of the pyrrol rings I and III in creases (es pe -
cially of N33 and N34 at oms), while the vi bra tions of CmH
groups and pyrrol rings II and IV de crease their am pli -
tude; at oms N35 and N36 shift to the op po site side, re -
gard ing at oms N33 and N34. (In the S and T states all N
at oms are headed to wards one di rec tion). The fre -
quency of these vi bra tions (mode 7) is ~80 cm–1 lower
than that in the S and T states (Ta ble 3), while in ten sity
in creases sig nif i cantly (26.0 km/mole).
The mode 18 (17 in Q state) is also char ac ter ised by
a large dis place ment of Fe(II) ion, yet only in ex cited
state, while in nor mal (quin tet) state, the dis place ment
of Fe(II) ion is 3–3.5 times lower (Ta ble 2), which, in
our opin ion, is con nected with sig nif i cant dif fer ences in
ge om e try of the mol e cule in Q state and con se quently
with the change in sym me try [11]. In this mode, in the
course of vi bra tion dur ing the out-of-plane dis place -
ment of Fe(II) ion and meth ane bridges, the pyrrol rings
bend in the op po site di rec tion. The range of fre quen -
cies re viewed (0–426 cm–1) is spe cific for the high est
in ten sity of this mode (Ta ble 3).
Ac cord ing to our cal cu la tions, in IR spec tra in the
range 427–653 cm–1, the vi bra tions of Fe(II)P are not
pres ent. The range of 653–906 cm–1 was re vealed to
have in tense out-of-plane vi bra tions of low dis place -
ment am pli tude (modes 33 and 38) with out dis place -
ment of Fe(II) ion (mode 49, Fig.3). There are also
asym met ri cal va lence vi bra tions of Fe–N bonds with
groups CbH, Cb¢H, and CmH of the be low-av er age in ten -
sity, with swing ing of the pyrrol rings and their pul sa -
tion as a re sult of skel e tal va lence vi bra tions of Ca–N
and Ca–Cb, or Ca¢–N and Ca¢–Cb¢ and the changes in an -
gles, pre sented in Ta ble 3 (modes 36(37), 42(43)).
Out-of-plane vi bra tion modes 38 and 49 were
shown to have the high est in ten sity in the cal cu lated IR
spec trum (103 and 164 km/mole, repectively, in the Q
state). If we re view the same out-of-plane vi bra tion
mode in the ex cited state, its vi bra tion fre quency will be
lower, than in the ground state, yet the fre quency de -
crease is only 1–4 cm–1.
Modes 33 and 38 are spe cific for the de crease in
am pli tude of the Fe and N at oms dis place ments dur ing
vi bra tion, while in mode 49 the vi bra tions of these at -
oms do not take place (Ta ble 3, Fig.3). Mode 49 is the
525
IN VES TI GA TION OF IN FRA RED SPEC TRUM OF Fe(II) PORPHIN
Fig.2 Shape of vi bra tion mode 3 in IR spec trum of Fe(II)P
last one among the out-of-plane vi bra tions, al lowed in
the IR spec trum. The cal cu la tions for the S state for the
modes 33, 38, and 49 with fre quen cies 723, 790, and
902 cm–1, re spec tively, us ing the same ba sis for the vi -
bra tion spec trum of H2P mol e cule cor re spond to the fre -
quen cies 713, 804, and 876 cm–1, which, tak ing into ac -
count zoom mul ti plier 0.975, amounts to 695, 784, and
854 cm–1, re spec tively. Ex per i men tal val ues of fre -
quen cies for H2P (691, 785, and 852 cm–1) are in a good
agree ment with our cal cu la tions.
Thus, the cor re la tion be tween data of these bands in
IR spec tra of H2P and Fe(II)P us ing the method
B3LYP/6-311G was de ter mined, and in our opin ion,
this method will al low ob tain ing re li able re sults for cal -
cu la tion of IR spec tra of iron porphyrin and its de riv a -
tives.
The vi bra tions close to 1 000 cm–1 (modes 55(56),
59(60) in S, and cor re spond ing modes in T and Q states)
are as sisted by Fe–N bonds (asym met ri cal vi bra tions)
with Fe atom shift (0.02–0.03 a.u.), yet their con tri bu -
tion to a gen eral form of this vi bra tion is in sig nif i cant.
Dom i nant con tri bu tion is made by va lence vi bra tions of
the Ca–N (Ca¢–N) and Ca–Cb (Ca¢–Cb¢) bonds, at the
same time sym met ri cal vi bra tions re sult in the pul sa tion
of the rings, whereas asym met ri cal ones re sult in their
twist ing.
Later vi bra tion modes were not ob served to have
the dis place ment of Fe atom, ex cept for modes 71 (72)
in T state. Modes 55 (56) are spe cific for high in ten sity
in all elec tronic states un der in ves ti ga tion, while in ten -
sity in modes 59 and 60 in the T state de creased sig nif i -
cantly (down to 2.3 km/mole).
The range of fre quen cies 1100 – 1285 cm–1 is dom i -
nated by the in-plane deformational CH-vi bra tions of
Fe(II)P. In tense vi bra tion modes 63 and 64, fre quency
~1100 cm–1, are con trib uted mostly by deformational
CH-vi bra tions of pyrrol rings with changes of an gles
CaCbH (Ca¢Cb¢H) and CbCbH (Cb¢Cb¢H). Low-in ten sity
deformational CmH vi bra tions with changes of an gles
CaCmH (Ca¢CmH) along with CH-vi bra tions of pyrrol
rings are ob tained at the fre quency of 1170 and 1270
cm–1. Pyrrol ring bonds Ca–N, Ca–Cb, and Cb–Cb take
part in the vi bra tions in the range of 1100–1285 cm–1.
Asym met ri cal vi bra tions of Fe–N bond are ex pired at
1285 cm–1. In the modes 71(72) the dis place ment of
Fe(II) ion dur ing vi bra tion (0.01 a.u.) takes place only
in T state, and in the modes 67 and 68 an asym met ri cal
va lence vi bra tion of Fe–N bonds take place with out any
dis place ment of Fe(II) ion.
In IR spec trum of Fe(II)P in the range of
1300–1642 cm–1 there are some skel e tal vi bra tions of
the methine bridges and pyrrol rings, whereas at the in -
526
MINAEV B. F., MINAEV A. B., HOVORUN D. N.
Fig.3 Shape of vi bra tion mode 49 in IR spec trum of Fe(II)P
crease in the fre quency the con tri bu tion of Ca–Cm vi bra -
tions in creases and de creases of the Ca–N con tri bu tion.
Thus, vi bra tion modes 73 and 74 are pre dom i nantly
con trib uted by nas(Ca¢–N) and nas(Ca–N) re spec tively,
while in modes 90, 91 asym met ri cal va lence vi bra tions
Ca–Cm and Ca¢–Cm are more com mon. Along with the
lat ter vi bra tions, there are deformational vi bra tions of
CbH- and CmH groups with sig nif i cant dis place ment
am pli tude with an gles CCbH (CCb¢H) and CCmH. The
change in vi bra tion fre quency and the in ten sity of vi -
bra tion modes ob served dur ing the tran si tion from nor -
mal to ex cited states did not re veal any reg u lar i ties,
gen er ally the in ten sity of vi bra tion modes in the range
of fre quen cies of 1300–1642 cm–1 is close to the av er -
age in ten sity or be low av er age.
The range of fre quen cies of 1650–3255 cm–1 is spe -
cific for three de gen er ate vi bra tion modes, be long ing to
va lence vi bra tions of C–H bonds (Ta ble 3), among
which Cm–H bonds take part in modes 95 and 96, and
Cb–H bonds take part in modes 99, 100, 103, 104. The
vi bra tion of Cm–H bonds is spe cific for lower fre -
quency, than in the case of Cb–H. Sym met ri cal vi bra -
tions of Cb–H bonds were ob tained at higher fre quen -
cies and shown to be more in tense than the asym met ri -
cal ones. In the Q state, vi bra tion fre quen cies of C–H
stretch ing modes are lower than in the S and T states and
vi bra tion modes are spe cific for higher in ten sity. This
con clu sion is a gen eral cri te rion of iden ti fi ca tion of the
higher spin state of Fe(II)P and we con sider it to be true
for all hemoproteins. The cal cu lated IR ab sorp tion
spec trum of Fe(II)P mol e cule in the Q state is pre sented
in Fig.4 with out ac count of the zoom mul ti plier.
The cal cu la tions of Fe(II)-porphin com plexes with
dif fer ent types of ax ial lig ands us ing DFT as well as
some other ap proaches are cur rently in prog ress.
Cen tral as pect of hemoprotein dy nam ics is the dis -
place ment of Fe(II) ion from the plane of porphin
macrocycle. The in ves ti ga tion of deoxymyoglobin us -
ing Mossbauer effect re vealed that at low tem per a ture
the mo tion of Fe(II) ion in the ac tive cen tre of heme
with one ax ial ligand cor re sponds to har monic vi bra -
tions, yet at 165 K this mo tion be comes anharmonical
and is ac com pa nied by a rapid in crease in am pli tude [8,
21]. This be hav iour may be ex plained by the change in
the spin di rec tion (flip-over) by means of spin-or bit in -
ter ac tion be tween two neigh bour ing multiplet states of
Fe(II)P [7, 21]. At the same time the out-of-plane vi -
bra tion mode, con nected with dis place ment of Fe(II)
ion, should have dif fer ent fre quen cies and equi lib rium
po si tions in these states [8, 11]. The cal cu lated IR spec -
trum of Fe(II)P mol e cule re vealed the sharp change of
vi bra tion fre quen cies of modes 3 and 7 in the Q state,
com pared to the T and S states. The in ten sity of IR ab -
sorp tion of vi bra tion mode 7 is known to in crease sig -
nif i cantly as well. The Q state was also re vealed to ex -
pend in Fe(II) frame in porphin macrocycle [11]. Our
cal cu la tion does not con firm Fe(II) ion to leave the
plane of porphin macrocycle at the quin tet state equi lib -
rium, which is in good agree ment with re sults, de -
scribed in Ref. [8]. It is quite pos si ble that the force
field in quin tet state is soft ened sig nif i cantly, which as -
sists leav ing of Fe(II) ion from the macrocycle plane. It
may be con sid ered that in deoxymyoglobin the
out-of-plane dis place ments of Fe(II) ion take place eas -
ily un der the in flu ence of pro teins.
Con clu sions. Sharp in crease in in ten sity of vi bra -
tion mode 7 in the Q state as well as sig nif i cant dis -
place ment of its fre quency (from 290 to 208 cm–1), in
com par i son with the cor re spond ing modes 14 (S) and
12 (T) in lower-spin states is the most im por tant re sult
of the pres ent work. The low-fre quency IR range
(300–200 cm–1) is open for mod ern spec tral in ves ti ga -
tions and its anal y sis pro vides a re li able cri te rion for
iden ti fi ca tion of the spin state.
527
IN VES TI GA TION OF IN FRA RED SPEC TRUM OF Fe(II) PORPHIN
Fig.4 IR ab sorp tion spec tra in quin tet state, cal cu lated by the
B3LYP/6-311G method (max i mum in ten sity is 163.6 km/mole;
band half-width is 20 cm–1)
In crease in IR in ten sity of the vi bra tion mode 7 in
the Q state in di cates a sig nif i cant change in elec tronic
den sity dur ing the dis place ment of at oms in this mode,
which is a spe cific fea ture of oc cu pa tion of 3dx2–y2 or -
bital, which is of nap ping char ac ter in re gards to Fe–N
bonds. That is why the out-of-plane bend ing of these
bonds takes place in a dif fer ent way in the Q and in the S
and T states of Fe(II)P, which also de ter mines the shift
of fre quen cies and in ten si ties. The spec i fic ity of these
dis place ments de pend ing on the spin is of great in ter est
for fu ture ex per i men tal in ves ti ga tions of spin dy nam ics
and iden ti fi ca tion of spins of hemoproteins.
The work was sup ported by State Fund of Fun da -
men tal Re search F 25.5 /008 Spin-ca tal y sis in bio chem -
i cal pro cesses with par tic i pa tion of Cytochrom P450
and other iron-por phy rins
Á. Ô. Ìèíàåâ, À. Á. Ìèíàåâ, Ä. Í. Ãîâîðóí
Èññëåäîâàíèå èíôðàêðàñíîãî ñïåêòðà ìîëåêóëû Fe(II)-
ïîðôèíà â ðàçíûõ ñïèíîâûõ ñîñòîÿíèÿõ êâàíòîâî-õèìè÷åñêèì
ìåòîäîì ôóíêöèîíàëà ïëîòíîñòè
Ðåçþìå
Êâàíòîâî-õèìè÷åñêèì ìåòîäîì òåîðèè ôóíêöèîíàëà
ïëîòíîñòè ðàññ÷èòàíû èíôðàêðàñíûå (ÈÊ) ñïåêòðû
ïîãëîùåíèÿ ìîëåêóëû Fe(II)-ïîðôèíà äëÿ ñèíãëåòíîãî,
òðèïëåòíîãî è êâèíòåòíîãî ñïèíîâûõ ñîñòîÿíèé. Äëÿ
îïòèìèçàöèè ãåîìåòðèè è ðàñ÷åòà ÈÊ ñïåêòðà èñïîëüçîâàí
íåîãðàíè÷åííûé ïî ñïèíó ôóíêöèîíàë UB3LYP â áàçèñå 6-311G.
Ïîêàçàíî, ÷òî êâèíòåòíîå ñîñòîÿíèå 5B2g ñèììåòðèè D2h
ÿâëÿåòñÿ îñíîâíûì. Äëÿ òðèïëåòíîãî ñîñòîÿíèÿ ñ íèçêîé
ýíåðãèåé 3À2g è ñèíãëåòíîãî ñîñòîÿíèÿ ñ âûñîêîé ýíåðãèåé 1À1g,
èìåþùèõ ñèììåòðèþ D4h, ÈÊ ñïåêòðû èçó÷åíû â òî÷å÷íîé
ãðóïïå ñèììåòðèè D2h. Ïðîàíàëèçèðîâàíû âñå àêòèâíûå â ÈÊ
ñïåêòðå êîëåáàòåëüíûå ìîäû. Â êâèíòåòíîì ñîñòîÿíèè
íèçêî÷àñòîòíûå âíåïëîñêîñòíûå êîëåáàòåëüíûå ìîäû ñ
áîëüøèì ñìåùåíèåì èîíà Fe(II) èìåþò ðàçëè÷íûå
èíòåíñèâíîñòè è ÷àñòîòíûå ñäâèãè ïî ñðàâíåíèþ ñ
ñèíãëåòíûì è òðèïëåòíûì ñîñòîÿíèÿìè.
Êëþ÷åâûå ñëîâà: Fe(II)-ïîðôèí, ñèíãëåò, òðèïëåò,
êâèíòåò, ñïèíîâûå ñîñòîÿíèÿ, òåîðèÿ ôóíêöèîíàëà
ïëîòíîñòè, ÈÊ ñïåêòð ïîãëîùåíèÿ, íèçêî÷àñòîòíûå ìîäû.
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UDC 577.175.6:544.18:543.422
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MINAEV B. F., MINAEV A. B., HOVORUN D. N.
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