有机染料敏化剂JK16和JK17的几何结构、电子结构及相关性质

运用密度泛函理论中的杂化泛函B3LYP研究了高效太阳能电池新型染料敏化剂JK16和JK17的几何结构、电子结构、极化率和超极化率, 并用含时密度泛函理论(TDDFT)研究了电子吸收谱. 基于含时密度泛函理论计算结果和实验结果的定性符合, 指认了在可见和近紫外区的吸收属于π→π*跃迁. 计算结果还表明JK16和JK17激发能最低的三个跃迁都与光诱导电荷转移过程有关, 而且二-二甲基芴氨基苯并噻吩基团对光电转换过程的敏化起主要作用, 发生于染料敏化剂JK16、JK17和TiO2界面之间的电荷转移是由染料分子激发态向半导体导带的电子注入过程. 此外, 通过对JK16和JK17的比较, 分析了亚乙烯基对几何结构、电子结构和谱学特性的影响.     

1H NMR investigation of high-spin and low-spin iron(III) meso-ethynylporphyrins

The 1H NMR spectra of iron(III) 5-ethynyl-10,15,20-tri(p-tolyl)porphyrin [(ETrTP)Fe(III)X(n)], iron(III) 5-(phenylethynyl)-10,15,20-tri(p-tolyl)porphyrin [(PETrTP)Fe(III)X(n)], iron(III) 5-(phenylbutadiynyl)-10,15,20-tri(p-tolyl)porphyrin [(PBTrTP)Fe(III)X(n)], iron(III) 5,10,15,20-tetra(phenylethynyl)porphyrin [(TPEP)Fe(III)X(n)], iron(III) 1,4-bis-[10,15,20-tri(p-tolyl)porphyrin-5-yl]-1,3-butadiyne {[(TrTP)Fe(III)X(n)]2 B}, and 5,10,15-triphenylporphyrin [(TrPP)Fe(III)X(n)] have been studied to elucidate the impact of meso-ethynyl substitution on the electronic structure and spin density distribution of high-spin (X = Cl-, n = 1) and low-spin (X = CN-, n = 2) derivatives. The meso substituents, i.e., ethynyl, phenylethynyl, and phenylbutadiynyl, provided insight into the efficiency of spin density delocalization along structural elements that are typically applied to transmit electronic effects along multipart polyporphyrinic systems. The positive spin density localized at the meso-carbon of high-spin iron(III) ethynylporphyrins is effectively delocalized along the ethyne or butadiyne fragment as illustrated by the comparison of isotropic shifts of C(meso)-H and -CC-H determined for (TrPP)Fe(III)Cl (-82.6 ppm, 293 K) and (ETrTP)Fe(III)Cl (-49.5 ppm, 298 K). The replacement of the ethynyl hydrogen by phenyl or phenylethynyl provided evidence for the pi spin density distribution around the introduced phenyl ring. An analysis of the isotropic shifts for the low-spin bis-cyanide iron(III) porphyrins series reveals the analogous mechanism of spin density transfer. Treatment of high-spin [(TrTP)Fe(III)Cl]2 B with a base resulted in formation of the cyclic [(TrTP)Fe(III)OFe(III)(TrTP)B]2 complex linked by two mu-oxo bridges. (TPEP)H2 has been characterized by X-ray crystallography as a porphyrin dication where two molecules of trifluoroacetic acid associate with two coordinated trifluoroacetate anions. The X-ray structure of bis-tetrahydrofuran 1,4-bis[10,15,20-tri(p-tolyl)porphyrinatozinc(II)-5-yl]-1,3-butadiyne complex {[(TrTP)Zn(II)(THF)]2 B} reveals two parallel, non-coplanar [(TrTP)Zn(THF)] subunits linked by the linear butadiyne moiety.     

Theoretical study of the electronic spectra of square-planar platinum (II) complexes based on the two-component relativistic time-dependent density-functional theory

In the present work the electronic spectra of [PtCl(4)](2-), [PtBr(4)](2-), and [Pt(CN)(4)](2-) are studied with a recently proposed relativistic time-dependent density-functional theory (TDDFT) based on the two-component zeroth-order regular approximation and a noncollinear exchange-correlation (XC) functional. The contribution to the double group excited states in terms of singlet and triplet single group excited states is estimated through the inner product of the transition density matrix obtained from two-component and scalar relativistic TDDFT calculations to better understand the double group excited states. Spin-orbital coupling effects are found to be very important in order to simulate the electronic spectra of these complexes. The results show that the two-component TDDFT formalism can afford excitation energies with high accuracy for the transition-metal systems studied here when use is made of a proper XC potential.     

A visible light photocatalyst: effects of vanadium substitution on ETS-10

Hybrid density functional theory/molecular mechanics (DFT/MM) methods have been used to investigate the effects of vanadium substitution in ETS-10. Models have been developed to contain varying concentrations of V(IV) and V(V) within the O-M-O (M = Ti, V) chain. Most of the V-substituted models have a localized mid-gap state. The occupation of this localized state depends upon the dopant oxidation state, leading to the addition of multiple low energy transitions. A linear correlation has been identified between band gap energies estimated using ground state orbital energies and those calculated using the more accurate and computationally demanding time-dependent DFT (TDDFT) method for a variety of transition metal substituted models of ETS-10. Consistent with experimental data for V substitution, our models predict a decrease in the optical band gap with increasing [V], due to a lowering of the delocalized d-orbital states at the bottom of the conduction band with increasing V d-orbital character. This effect is more pronounced in the case of V(V) substitution than V(IV). Excitation energies for the V-doped models, calculated with TDDFT methods correlate well with experimental data, allowing for the assignment of specific optical transitions to experimental UV-Vis spectra. The electronic structure of V-substituted ETS-10 at high V concentration demonstrates band gap energies within the visible range of the spectrum. Additionally, at high [V] the band gap energy and presence of low energy electron traps can be controlled by the relative concentration of V(IV) and V(V) along the O-M-O chain, establishing V-substituted ETS-10 as a promising visible light photocatalyst.     

Theoretical study on the chiroptical optical properties of chiral fullerene C60 derivative

Time-dependent density functional theory (TDDFT) calculations have been used to investigate UV/CD spectra and nonlinear optical (NLO) property of the C(60)-fullerene bisadduct (R,R,(f,s)A)-[CD(+)280] for the first time. The electron transition natures of the four main measured bands are analyzed, and their results are used to designate the excited states involved in an electron-transfer process of the studied compound. On a comparative scale, the predicted excitation energies and oscillator strengths are in reasonable agreement with the observed values, demonstrating the efficiency of TDDFT in predicting the localized and charge transfer transitions. The good agreement between the experimental and the simulated CD spectra shows that TDDFT calculations can be used to assign the absolute configurations (ACs) of chiral fullerene C(60) derivatives with high confidence. The observed large dissymmetry ratio g (g = Δε/ε) at about 700 nm results from the orbital characters of the local fullerene excited state, which leads to large transition magnetic dipole moment and small transition electronic dipole moment. The different functionals and solvent effects on UV/CD spectra were also considered. The studied compound has a possibility to be an excellent second-order NLO material from the standpoint of transparency and large second-order polarizability value.     

Synthesis, structure and characterization of fac-[Re(CO)3] complexes derived from hydrazone Schiff bases: DFT-TDDFT investigation on electronic structures

The syntheses, structural and spectroscopic characterization of the complexes of general formula [ReL(CO)₃Cl] bearing bifunctional hydrazone Schiff base ligand L are presented in this paper. The structure of one of the complexes is determined by X-ray crystallography. The solid-state structure of the compound is involved in a secondary interaction in lattice forming a supramolecular array. The gas phase geometry optimization and electronic calculation have been performed using density functional theory without any symmetry constraints. On the basis of structural and theoretical studies, ligand in the complexes is considered to be in the keto, not in enol form. Experimental ground state IR and NMR data set agree with those calculated by DFT calculations. The electronic spectra of the complexes are calculated by time dependent density functional theory (TDDFT) using conductor like polarizable continuum model (CPCM). The computed vertical excitation energies in solution are in good agreement with experimental one showing that the metal-to-ligand charge transfer transitions in visible region dominate over ligand based ILCT transition. The TDDFT excited states calculation of the electronic spectra in solution provides evidence towards luminescence spectra.     

Syntheses, characterization and redox properties of oxo-centred triruthenium cluster dimers and trimers linked by ortho-metallated polypyridyl ligands

A series of mono-, di- and trimeric oxo-centred triruthenium cluster compounds with ortho-metallated polypyridyl ligands were prepared by reaction of oxo-centred triruthenium precursor compound [Ru3O(OAc)6(py)2(CH3OH)]+ (1) with bis(2,2'-bipyridin-5-yl)butadiyne (bpyC[triple bond, length as m-dash]C-C[triple bond, length as m-dash]Cbpy), bis(2,2'-bipridin-5-yl)ethyne (bpyC[triple bond, length as m-dash]Cbpy), 2,2'-bipyrazine (bpz), pyrazino[2,3-f]quinoxaline (pyq), or 4,7-phenanthroline (4,7-phen). As revealed by redox wave splitting, electronic interactions are operating between two Ru3O redox centres in most of the triruthenium cluster dimers and trimers. The cluster-cluster interactions are highly sensitive to the variations in bonding modes of the polypyridyl ligands. Ortho-metallation of the bridging ligand induces an enhanced electronic interaction between two triruthenium centres.     

A theoretical, spectroscopic, and photophysical study of 2,7-carbazolenevinylene-based conjugated derivatives

A combined theoretical and experimental study of the structure, optical, and photophysical properties of four 2,7-carbazolenevinylene-based derivatives in solution is presented. Geometry optimizations of the ground states of PCP, PCP-CN, TCT, and TCT-CN were carried out using the density functional theory (DFT/B3LYP/6-31G*). It is found that PCP and TCT are nearly planar in their ground electronic states (S0), whereas the cyano derivatives are more twisted. The nature and the energy of the first singlet-singlet electronic transitions have been obtained from time-dependent density functional theory (TDDFT) calculations performed on the optimized geometries. For all the compounds, excitation to the S1 state corresponds mainly to the promotion of one electron from the highest-occupied molecular orbital to the lowest-unoccupied molecular orbital, and the S1 <-- S0 electronic transition is strongly allowed and polarized along the long axis of the molecular frame. The optimization (relaxation) of the first singlet excited electronic state (S1) has been done using the restricted configuration interaction (singles) (RCIS/6-31G*) approach. It is observed that all four investigated compounds become more planar in their S1 relaxed excited state. Electronic transition energies from the relaxed excited states have been obtained from TDDFT calculations performed on the S1-optimized geometries. The absorption and fluorescence spectra of the carbazolenevinylenes have been recorded in chloroform. A good agreement is obtained between TDDFT vertical transitions energies and the (0,0) absorption and fluorescence bands. The change from phenylene to thiophene rings as well as the incorporation of cyano substituents induce bathochromic shifts in the absorption and fluorescence spectra. From the analysis of the energy of the frontier molecular orbitals, it is believed that thiophene rings and CN substituents induce some charge-transfer character to the first electronic transition, which is responsible for the red shifts observed. Finally, the fluorescence quantum yield and the lifetime of the compounds in chloroform have been obtained. In sharp contrast with many oligothiophenes, it is observed that TCT possesses a high fluorescence quantum yield. On the other hand, the CN-containing derivatives exhibit much lower fluorescence quantum yields, probably due to the combined influence of steric effects and charge-transfer interactions caused by the cyano groups.     

Potentiometric, electronic structural, and ground- and excited-state optical properties of conjugated bis[(porphinato)zinc(II)] compounds featuring proquinoidal spacer units

We report the synthesis, optical, electrochemical, electronic structural, and transient optical properties of conjugated (porphinato)zinc(II)-spacer-(porphinato)zinc(II) (PZn-Sp-PZn) complexes that possess intervening conjugated Sp structures having varying degrees of proquinoidal character. These supermolecular PZn-Sp-PZn compounds feature Sp moieties {(4,7-diethynylbenzo[c][1,2,5]thiadiazole (E-BTD-E), 6,13-diethynylpentacene (E-PC-E), 4,9-diethynyl-6,7-dimethyl[1,2,5]thiadiazolo[3,4-g]quinoxaline (E-TDQ-E), and 4,8-diethynylbenzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole) (E-BBTD-E)} that regulate frontier orbital energy levels and progressively increase the extent of the quinoidal resonance contribution to the ground and electronically excited states, augmenting the magnitude of electronic communication between terminal (5,-10,20-di(aryl)porphinato)zinc(II) units, relative to that evinced for a bis[(5,5',-10,20-di(aryl)porphinato)zinc(II)]butadiyne benchmark (PZnE-EPZn). Electronic absorption spectra show significant red-shifts of the respective PZn-Sp-PZn x-polarized Q state (S0 --> S1) transition manifold maxima (240-4810 cm(-1)) relative to that observed for PZnE-EPZn. Likewise, the potentiometrically determined PZn-Sp-PZn HOMO-LUMO gaps (E1/2(0/+) - E1/2(-/0)) display correspondingly diminished energy separations that range from 1.88 to 1.11 eV relative to that determined for PZnE-EPZn (2.01 eV). Electronic structure calculations provide insight into the origin of the observed PZn-Sp-PZn electronic and optical properties. Pump-probe transient spectral data for these PZn-Sp-PZn supermolecules demonstrate that the S1 --> S(n) transition manifolds of these species span an unusually broad spectral domain of the NIR. Notably, the absorption maxima of these S1 --> S(n) manifolds can be tuned over a 1000-1600 nm spectral region, giving rise to intense excited-state transitions approximately 4000 cm(-1) lower in energy than that observed for the analogous excited-state absorption maximum of the PZnE-EPZn benchmark; these data highlight the unusually large quinoidal resonance contribution to the low-lying electronically excited singlet states of these PZn-Sp-PZn species. The fact that the length scales of the PZn-Sp-PZn species (approximately 25 angstrom) are small with respect to those of classic conducting polymers, yet possess NIR S1 --> S(n) manifold absorptions lower in energy, underscore the unusual electrooptic properties of these conjugated structures.     

Photophysics and spectroscopy of the higher electronic states of zinc metalloporphyrins: a theoretical and experimental study

The photophysics of the S2 and S1 excited states of zinc porphyrin (ZnP) and five of its derivatives (ZnOEP, ZnTBP, ZnTPP, ZnTFPP, ZnTCl8PP) have been investigated by measuring their steady-state absorption and fluorescence spectra, quantum yields and excited state lifetimes at room temperature in several solvents. The radiative and radiationless decay constants of the fluorescent excited states accessible in the visible and near UV regions of the spectrum have been obtained. Despite the similarities in the Soret spectra of these compounds, their S2 excited state radiationless decay rates differ markedly. Although the S2-S1 electronic energies of a given zinc porphyrin vary linearly with the Lippert (refractive index) function of the solvent, the S2 radiationless decay rates of the set of compounds do not follow the energy gap law of radiationless transition theory. Calculations, using time-dependent density functional theory (TDDFT), of the energies and symmetries of the complete set of excited states accessible by 1- or 2-photon absorption in the near UV-visible have also been carried out. Substitution on the porphyrin macrocycle framework affects the ground state geometry and alters the electron density distributions, the orbital energies and the relative order of the excited electronic states accessible in the near UV-blue regions of the spectrum. The results are used to help interpret both the nature of the electronic transitions in the Soret region, and the relative magnitudes of the radiationless transition rates of the excited states involved.     

A simplified relativistic time-dependent density-functional theory formalism for the calculations of excitation energies including spin-orbit coupling effect

In the present work we have proposed an approximate time-dependent density-functional theory (TDDFT) formalism to deal with the influence of spin-orbit coupling effect on the excitation energies for closed-shell systems. In this formalism scalar relativistic TDDFT calculations are first performed to determine the lowest single-group excited states and the spin-orbit coupling operator is applied to these single-group excited states to obtain the excitation energies with spin-orbit coupling effects included. The computational effort of the present method is much smaller than that of the two-component TDDFT formalism and this method can be applied to medium-size systems containing heavy elements. The compositions of the double-group excited states in terms of single-group singlet and triplet excited states are obtained automatically from the calculations. The calculated excitation energies based on the present formalism show that this formalism affords reasonable excitation energies for transitions not involving 5p and 6p orbitals. For transitions involving 5p orbitals, one can still obtain acceptable results for excitations with a small truncation error, while the formalism will fail for transitions involving 6p orbitals, especially 6p1/2 spinors.     

Ground and excited state properties of photoactive platinum(IV) diazido complexes: theoretical considerations

Recently synthesized by the group of Sadler, the platinum(IV) diazido complexes [Pt(N(3))(2)(OH)(2)(L')(L')] (L' and L' are N-donor ligands) have potential to be used as photoactivatable metallodrugs in cancer chemotherapy. In the present study optimized structures and UV-Vis electronic spectra of trans,trans,trans- and cis,trans,cis-[Pt(N(3))(2)(OH)(2)(NH(3))(2)] (1t and 1c, respectively) as well as cis,trans,cis-[Pt(N(3))(2)(OH)(2)(L)(2)] (L = NH(3), NH(2)CH(3), NF(3), PH(3), PF(3), H(2)O, CO, OH(-), CN(-), py, imid; 2c-11c) and cis,trans-[Pt(N(3))(2)(OH)(2)(bpy)] (12c) complexes were predicted using density functional theory (DFT). The ground state electronic structures of all complexes were analyzed with the help of the natural bond orbital analysis (NBO). The electronic spectra of 1c and 1t were computed using time-dependent density functional theory (TDDFT) with five different density functionals and the ab initio CASSCF/CASPT2 method (for the five lowest energy transitions). The best agreement with available experiments was found in the case of the long-range corrected ωB97X functional. The electronic transitions were characterized by the analysis of the natural transition orbitals (NTO). The low-lying excited singlet states of 1t and 1c have significant azide-to-platinum(IV) charge-transfer character (LMCT). Geometry optimization of the three lowest singlet excited states performed using TDDFT results in the simultaneous dissociation of two azide ligands with the formation of the azidyl radicals N(3)˙ and photoreduction of Pt(IV) to Pt(II). Variation of the ligand L does not strongly affect the nature and the relative energies of the low-lying states. It is shown that the replacement of the OH(-) groups in 1c by OPh(-) ligands results in the red shift of the intense N(3)(-)→Pt LMCT band and the appearance of transitions with significant intensity in the visible region of the spectrum. The dissociative nature of the low-lying unoccupied orbitals remains unaffected. These theoretical results may suggest new experimental routes for the improvement of the photochemical activity of Pt(IV) diazido complexes.     

Syntheses, structural characterizations, and optical and electrochemical properties of directly fused diporphyrins

Directly fused diporphyrins display the extensive pi conjugation as evinced by highly perturbed electronic absorption spectra as well as lowered and largely split first oxidation potentials. Such diporphyrins prepared include meso-beta doubly linked diporphyrins 7, meso-meso beta-beta beta-beta triply linked diporphyrins 8, and meso-meso beta-beta doubly linked diporphyrins 9. Oxidation of 5,15-diaryl-substituted and 5,10,15-triaryl-substituted Ni(II)-, Cu(II)-, and Pd(II)-porphyrins with tris(4-bromophenyl)aminium hexachloroantimonate (BAHA) in CHCl(3) afforded 7, and triply linked Cu(II)-diporphyrins 8a and 8g were respectively prepared by the oxidation of meso-meso singly linked Cu(II)-diporphyrins 5c and 5f with BAHA. Meso-meso beta-beta doubly linked Ni(II)-diporphyrin 9a was isolated along with triply linked Ni(II)-diporphyrin 8e from the similar oxidation of meso-meso singly linked Ni(II)-diporphyrin 5a. Doubly linked diporphyrins 7 and 9a both exhibit significantly perturbed electronic absorption spectra, in which the Soret-like bands are largely split at around 405-418 and 500-616 nm and the Q-bandlike absorption bands are substantially intensified and red-shifted at 748-820 nm, probably as a consequence of symmetry lowering. Triply linked diporphyrins 8 display more strongly perturbed electronic absorption spectra with split Soret-like bands at 408-419 and 567-582 nm and Q-bandlike absorption bands reaching far-infrared region. Structures of three types of fused diporphyrins 7b and 7c, 8g and 8j, and 9a have been unambiguously determined by X-ray crystallography to be nearly coplanar. Both the triply linked diporphyrins 8g and 8j exhibit very flat structures, whereas the doubly linked diporphyrins 7b and 7c exhibit ruffled structures. The doubly linked diporphyrin 9a shows a helically twisted conformation with larger ruffling toward the opposite directions and has been actually separated into two enantiomers, which display strong Cotton effects in the CD spectra. The first oxidation potentials (E(OX1)) decrease in the order of 5 > 7 > or = 9 > 8, indicating lift-up of HOMO orbital in this order, and split potential differences DeltaE = E(OX1) - E(OX2), in turn, increase in the reverse order of 5 < 7< or = 9 < 8. The (1)H NMR spectra have indicated that the aromatic porphyrin ring current becomes weakened in the order of 5 > 7 > 8. Collectively, the electronic interactions between the diporphyrins have been concluded to increase in the other of 5 < 7 < or = 9 < 8.     

Electronic structure, excited states, and photoelectron spectra of uranium, thorium, and zirconium bis(Ketimido) complexes (C5R5)2M[-NCPh2]2 (M = Th, U, Zr; R = H, CH3)

Organometallic actinide bis(ketimide) complexes (C5Me5)2An[-N=C(Ph)(R)]2 (where R = Ph, Me, and CH2Ph) of thorium(IV) and uranium(IV) have recently been synthesized that exhibit chemical, structural, and spectroscopic (UV-Visible, resonance-enhanced Raman) evidence for unusual actinide-ligand bonding. [Da Re et al., J. Am. Chem. Soc., 2005, 127, 682; Jantunen et al., Organometallics, 2004, 23, 4682; Morris et al., Organometallics, 2004, 23, 5142.] Similar evidence has been observed for the group 4 analogue (C5H5)2Zr[-N=CPh2]2. [Da Re et al., J. Am. Chem. Soc., 2005, 127, 682.] These compounds have important implications for the development of new heavy-element systems that possess novel electronic and magnetic properties. Here, we have investigated M-ketimido bonding (M = Th, U, Zr), as well as the spectroscopic properties of the highly colored bis-ketimido complexes, using density functional theory (DFT). Photoelectron spectroscopy (PES) has been used to experimentally elucidate the ground-state electronic structure of the thorium and uranium systems. Careful examination of the ground-state electronic structure, as well as a detailed modeling of the photoelectron spectra, reveals similar bonding interactions between the thorium and uranium compounds. Using time-dependent DFT (TDDFT), we have assigned the bands in the previously reported UV-Visible spectra for (C5Me5)2Th[-N=CPh2]2, (C5Me5)2U[-N=CPh2]2, and (C5H5)2Zr[-N=CPh2]2. The low-energy transitions are attributed to ligand-localized N p --> C=N pi excitations. These excited states may be either localized on a single ketimido unit or may be of the ligand-ligand charge-transfer type. Higher-energy transitions are cyclopentadienyl pi --> CN pi or cyclopentadienyl pi --> phenyl pi in character. The lowest-energy excitation in the (C5Me5)2U[-N=Ph2]2 compound is attributed to f-f and metal-ligand charge-transfer transitions that are not available in the thorium and zirconium analogues. Geometry optimization and vibrational analysis of the lowest-energy triplet state of the zirconium and thorium compounds also aids in the assignment and understanding of the resonance-enhanced Raman data that has recently been reported. [Da Re et al., J. Am. Chem. Soc., 2005, 127, 682.].     

Beyond vinyl: electronic structure of unsaturated propen-1-yl, propen-2-yl, 1-buten-2-yl, and trans-2-buten-2-yl hydrocarbon radicals

Vertical excitation energies and oscillator strengths for several valence and Rydberg electronic states of vinyl, propen-1-yl, propen-2-yl, 1-buten-2-yl, and trans-2-buten-2-yl radicals are calculated using the equation-of-motion coupled cluster methods with single and double substitutions (EOM-CCSD). The ground and the lowest excited state (n <-- pi) equilibrium geometries are calculated using the CCSD(T) and EOM-SF-CCSD methods, respectively, and adiabatic excitation energies for the n <-- pi state are reported. Systematic changes in the geometries, excitation energies, and Rydberg state quantum defects within this group of radicals are discussed.     

新型桥连双卟啉化合物的合成及结构表征

通过将4,4′-二羧基-2,2′-联吡啶、2,6-二溴甲基吡啶、2,6-二羟甲基吡啶和1,8-二氨基萘分别与5-(4-羟基苯基)-10,15,20-三苯基卟啉(1a)、5-(4-甲酰苯基)-10,15,20-三苯基卟啉(1b)和5-[4-(4′-溴代丁氧基)苯基]-10,15,20-三苯基卟啉(1c)反应,合成了3类新型的双卟啉化合物2a-2e,经IR,¹HNMR,MS,UV-Vis光谱及元素分析对中间体和目标化合物的结构进行了表征.     

A combined computational and experimental study of polynuclear Ru-TPPZ complexes: insight into the electronic and optical properties of coordination polymers

We report a combined experimental and computational study of polynuclear [Ru(n)(TPPZ)(n)(+1)](2)(n)(+) complexes, of interest in the field of photoactive polymers. The complexes with n = 1, 2, 3 and n > 5 have been synthesized and spectroscopically characterized. A red-shift of the visible band maximum from 2.59 to 2.03 eV is observed going from the monomer to the longer oligomeric species (n > 5). To characterize the geometries, electronic structure, and excited states of these complexes, density functional theory (DFT) and time-dependent DFT calculations on the [Ru(n)(TPPZ)(n)(+1)](2)(n)(+) series with n = 1-4 in solution have been performed. The agreement between experimental and calculated spectra is good, both in terms of absorption maximum energies and relative intensities for different values of n. For all the investigated complexes, we assign the main band in the visible region as a metal-to-metal plus ligand charge transfer (MMLCT) transition. The resulting excited states are delocalized throughout the entire complexes, as they originate from a superposition of pi(TPPZ)-t(2g)(Ru) states. The low-energy shoulder of the main visible absorption band, present in the experimental spectra for n > 1, is proposed to arise from spin-forbidden singlet-triplet transitions of similar MMLCT character, consistent with the observed enhancement of this feature in the spectra of the corresponding Os oligomers.