Long-lived emissions from 4'-substituted Pt(trpy)Cl+ complexes bearing aryl groups. Influence of orbital parentage

Pt(trpy)Cl+, where trpy denotes 2,2':6',2' '-terpyridine, is a versatile binding agent but has a limited photochemistry due to a short excited-state lifetime. However, this work shows that the introduction of aryl substituents at the 4' position of the trpy ligand drastically alters the picture. For the substituents phenyl, p-methoxyphenyl, 1-naphthyl, 2-naphthyl, 9-phenanthrenyl, and 1-pyrenyl, the ligand abbrevations are 4'-Ph-T, 4'-pMeOPh-T, 4'-Npl-T, 4'-Np2-T, 4'-Phe9-T, and 4'-Pyre1-T, respectively. Techniques utilized include electrochemistry as well as absorption and emission spectroscopies. While the lowest energy excited states of Pt(4'-Ph-T)Cl+ and the parent complex Pt(trpy)Cl+ exhibit mainly metal-to-ligand charge-transfer (MLCT) character, the emitting state takes on aryl-to-trpy intraligand charge-transfer (ILCT) character as the substituents become more electron-donating. Studies of Zn(trpy)Cl2, its aryl-substituted analogues, and the free ligands themselves provide information about the relative energies of participating ILCT and intraligand 3pi-pi excited states. Even though the emission energy decreases when larger aryl groups are present, the emission lifetime increases all the way from 85 ns for Pt(4'-Ph-T)Cl+ to 64 micros for Pt(4'-Pyre1-T)Cl+. (Data from deoxygenated, room-temperature dichloromethane solution.) Intraligand character appears to dominate in the case of Pt(4'-Pyre1-T)Cl+, which is unique in the series in that it exhibits singlet and triplet emissions in solution. In aerated solution the complex shows prompt as well as delayed fluorescence. Finally, studies in donor media establish that the introduction of intraligand character inhibits solvent-induced exciplex quenching.     

Synthesis, electrochemistry and luminescence of [Pt{4'-(R)trpy}(CN)](+) (R = Ph, o-CH(3)C(6)H(4), o-ClC(6)H(4) or o-CF(3)C(6)H(4); trpy = 2,2':6',2'-terpyridine): crystal structure of [Pt{4'-(Ph)trpy}(CN)]BF(4) x CH(3)CN

The synthesis and characterization of [Pt{4'-(R)trpy}(CN)]X (R = Ph, X = BF(4) or SbF(6); R = o-CH(3)C(6)H(4), X = SbF(6); R = o-ClC(6)H(4), X = SbF(6); or R = o-CF(3)C(6)H(4), X = SbF(6)) are described where trpy = 2,2':6',2'-terpyridine. Single crystals of [Pt{4'-(Ph)trpy}(CN)]BF(4).CH(3)CN were grown by vapour diffusion of diethyl ether into an acetonitrile solution of [Pt{4'-(Ph)trpy}(CN)]BF(4). An X-ray crystal structure determination of the solvated complex confirms the near linear coordination of the cyanide ligand to the platinum centre. The cation is almost planar as evidenced by a twist of only 1.9 degrees of the phenyl group out of the plane of the terpyridyl moiety. Cyclic voltammograms were recorded in DMF/0.1 M TBAH for the [Pt{4'-(R)trpy}(CN)](+) cations. Two quasi-reversible one-electron reduction (cathodic) waves are observed with E(1/2) values that show the trend expected for an increasingly lower energy of the trpy-based LUMO of the complex i.e., [Pt{4'-(Ph)trpy}(CN)](+) approximately [Pt{4'-(o-CH(3)C(6)H(4))trpy}(CN)](+) < [Pt{4'-(o-ClC(6)H(4))trpy}(CN)](+) < [Pt{4'-(o-CF(3)C(6)H(4))trpy}(CN)](+). All the [Pt(4'-(R)trpy}(CN)](+) cations are photoluminescent in dichloromethane. Emission by [Pt{4'-(Ph)trpy}(CN)](+) is from an excited state with largely (3)MLCT orbital parentage, but with some intraligand (3)pi-pi* character mixed-in (tau = 0.1 micros). In contrast, the other three cations display emission that appears exclusively intraligand (3)pi-pi* in origin (tau approximately 0.8 micros). Emission spectra have been recorded in a low concentration frozen DME {1 : 5 : 5 (v/v) DMF-MeOH-EtOH} glass. For the R = o-CH(3)C(6)H(4), o-ClC(6)H(4) and o-CF(3)C(6)H(4) cations the envelope of vibronic structure and energies of the vibrational components are essentially the same as that recorded in dichloromethane. However, for the [Pt{4'-(Ph)trpy}(CN)](+) cation, there is a blue-shift in the energies of the vibrational components as compared to that recorded in dichloromethane, as well as a change in the envelope of vibronic structure to a more "domed" pattern; this has been interpreted in terms of a higher percentage of intraligand (3)pi-pi* character in the emitting state for the glass. Increasing the concentration of the glass invariably leads to aggregation of the cations and the consequent development of new low energy bands, such that at 0.200 mM broad peaks centred at ca. 650 and 700 nm dominate the spectrum; these bands are assigned to excimeric (3)pi-pi* and (3)MMLCT emission, respectively.     

Theoretical study of the electronic structures and spectroscopic properties of [(4′-XC ≡ Ctrpy)PtCl]<Superscript>+</Superscript> (trpy = 2,2′:6′,2″-terpyridine; X = H,Me and Ph)

The electronic structures and spectroscopic properties of [(4′-XC≡Ctrpy)PtCl]⁺(trpy = 2,2′:6′,2″-terpyridine; X = H (1), methyl (Me) (2), and phenyl (Ph) (3) were studied by the ab initio method. The structures at the ground and excited state were optimized at the B3LYP and CIS levels, respectively. The absorption and emission spectra in the dichloromethane solution were obtained by using the TD-DFT (B3LYP) method associated with the PCM model. The molecular orbital energy of the HOMOs of 1–3 with the d(Pt), p(Cl), π(trpy), and π(XC≡C) character is sensitive to the substituents on the acetylide ligand, but that of the trpy-based LUMOs with the π*(trpy) character varies slightly. The lowest lying emission at 503 nm for 1 is mainly attributed to the ³ILCT perturbed by the ³MLCT and ³LLCT transitions, but that at 535 nm for 2, and that at 558 nm for 3 are mainly attributed to the ³LLCT perturbed by the ³ILCT and ³MLCT transitions. The different electron-donating ability of H, Me, and Ph is responsible for the differences in emission character. Moreover, the calculation results show that the phosphorescent color can be turned by adjusting the substituents. Both the lowest energy absorption and emission of 1–3 are red-shifted in the order of 1<2<3, consistent with the electron-donating of H<Me<Ph.     

Example of highly stereoregulated ruthenium amidine complex formation: synthesis,crystal structures,and spectral and redox properties of the complexes [Ru(II)(trpy)[NC(5)H(4)-CH=N-N(C(6)H(5))C(CH(3))=NH]](ClO(4))(2) (1) and [Ru(II)(trpy)(NC(5)H(4)-CH=N-NH-C(6)H(5))Cl]ClO(4) (2) (trpy = 2,2':6',2"-terpyridine)

The reaction of Ru(trpy)Cl(3) (trpy = 2,2':6',2"-terpyridine) with the pyridine-based imine function N(p)C(5)H(4)-CH=N(i)-NH-C(6)H(5) (L), incorporating an NH spacer between the imine nitrogen (N(i)) and the pendant phenyl ring, in ethanol medium followed by chromatographic work up on a neutral alumina column using CH(3)CN/CH(2)Cl(2) (1:4) as eluent, results in complexes of the types [Ru(trpy)(L')](ClO(4))(2) (1) and [Ru(trpy)(L)Cl]ClO(4) (2). Although the identity of the free ligand (L) has been retained in complex 2, the preformed imine-based potentially bidentate ligand (L) has been selectively transformed into a new class of unusual imine-amidine-based tridentate ligand, N(p)C(5)H(4)-CH=N(i)-N(C(6)H(5))C(CH(3))=N(a)H (L'), in 1. The single-crystal X-ray structures of the free ligand (L) and both complexes 1 and 2 have been determined. In 2, the sixth coordination site, that is, the Cl(-) function, is cis to the pyridine nitrogen (N(p)) of L which in turn places the NH spacer away from the Ru-Cl bond, whereas, in 1, the corresponding sixth position, that is, the Ru-N(a) (amidine) bond, is trans to the pyridine nitrogen (N(p)) of L'. The trans configuration of N(a) with respect to the N(p) of L' in 1 provides the basis for the selective L --> L' transformation in 1. The complexes exhibit strong Ru(II) --> pi* (trpy) MLCT transitions in the visible region and intraligand transitions in the UV region. The lowest energy MLCT band at 510 nm for 2 has been substantially blue-shifted to 478 nm in the case of 1. The reversible Ru(III)-Ru(II) couples for 1 and 2 have been observed at 0.80 and 0.59 V versus SCE, respectively. The complexes are weakly luminescent at 77 K, exhibiting emissions at lambda(max), 598 nm [quantum yield (Phi) = 0.43 x 10(-2)] and 574 nm (Phi = 0.28 x 10(-2)) for 1 and 2, respectively.     

Stepwise synthesis of [Ru(trpy)(L)(X)](n+) (trpy = 2,2':6',2' '-terpyridine; L = 2,2'-dipyridylamine; X = Cl-, H2O, NO2-, NO+, O2-). Crystal structure, spectral, electron-transfer, and photophysical aspects

Ruthenium-terpyridine complexes incorporating a 2,2'-dipyridylamine ancillary ligand [Ru(II)(trpy)(L)(X)](ClO(4))(n) [trpy = 2,2':6',2' '-terpyridine; L = 2,2'-dipyridylamine; and X = Cl(-), n = 1 (1); X = H(2)O, n = 2 (2); X = NO(2)(-), n = 1 (3); X = NO(+), n = 3 (4)] were synthesized in a stepwise manner starting from Ru(III)(trpy)(Cl)(3). The single-crystal X-ray structures of all of the four members (1-4) were determined. The Ru(III)/Ru(II) couple of 1 and 3 appeared at 0.64 and 0.88 V versus the saturated calomel electrode in acetonitrile. The aqua complex 2 exhibited a metal-based couple at 0.48 V in water, and the potential increased linearly with the decrease in pH. The electron-proton content of the redox process over the pH range of 6.8-1.0 was calculated to be a 2e(-)/1H(+) process. However, the chemical oxidation of 2 by an aq Ce(IV) solution in 1 N H(2)SO(4) led to the direct formation of corresponding oxo species [Ru(IV)(trpy)(L)(O)](2+) via the concerted 2e(-)/2H(+) oxidation process. The two successive reductions of the coordinated nitrosyl function of 4 appeared at +0.34 and -0.34 V corresponding to Ru(II)-NO(+) --> Ru(II)-NO* and Ru(II)-NO* --> Ru(II)-NO(-), respectively. The one-electron-reduced Ru(II)-NO* species exhibited a free-radical electron paramagnetic resonance signal at g = 1.990 with nitrogen hyperfine structures at 77 K. The NO stretching frequency of 4 (1945 cm(-1)) was shifted to 1830 cm(-1) in the case of [Ru(II)(trpy)(L)(NO*)](2+). In aqueous solution, the nitrosyl complex 4 slowly transformed to the nitro derivative 3 with the pseudo-first-order rate constant of k(298)/s(-1) = 1.7 x 10(-4). The chloro complex 1 exhibited a dual luminescence at 650 and 715 nm with excited-state lifetimes of 6 and 1 micros, respectively.     

(2,2':6',2' '-Terpyridine)platinum(II) complexes containing (thioalkyl)dicarba-closo-dodecaborane(12) ligands

A series of novel platinum(II)-2,2':6',2' '-terpyridine (trpy) complexes containing (thioalkyl)dicarba-closo-dodecaborane(12) (closo-carborane) derivatives were prepared by treatment of the labile precursor species [Pt(MeCN)(trpy)](OTf)2 with R(CH2)nSH (R = closo-1,2-carborane, n = 0-3; R = closo-1,7-carborane, n = 1; R = closo-1,12-carborane, n = 1) in the presence of NEt3 to afford brightly colored complexes of the type [PtS(CH2)nR(trpy)]OTf. All products were characterized by means of multinuclear (1H, 13C, 11B, and 195Pt) 1D- and 2D-NMR spectroscopy, ESI-MS, and, for the 1,7-carborane derivative, X-ray crystallography. Preliminary in vitro cytotoxicity studies of selected complexes against human ovarian carcinoma cells are also reported.     

三联吡啶Pt(Ⅱ)配合物的基态和激发态的理论研究

为了探究取代基对三联吡啶Pt(Ⅱ)配合物发光性质的影响, 采用MP2和CIS方法分别对配合物[Pt(trpy)C≡CC6H4R]+[trpy=2,2',6',2″-Terpyridine; R=NO2(1), Cl(2), H(3), CH3(4)]的基态和激发态的几何构型进行了优化, 通过TDDFT/B3LYP方法得到了这些化合物在二氯甲烷溶液中的磷光发射光谱以及它们的跃迁性质. 研究结果表明, 由于NO2的强吸引作用以及在C≡CC6H4NO2部分可能存在的电子共振结构, 化合物1的最低发射可以指认为Pt—C≡C→trpy(3MLCT/3LLCT) 的跃迁, 并且还有很大的一部分来自于π→π*(C6H4NO2) 跃迁的贡献, 而化合物3和化合物4由于含有给电子基团, 因此其最低发射仅仅是来自于3MLCT/3LLCT的跃迁. 但是并不是所有的取代基为吸电子基团时都能有类似的π→π*跃迁性质. 对于化合物2, Cl是仅次于NO2的吸电子取代基, 但是由于缺少电子共振的贡献, 它的跃迁性质却与化合物3和4相同. 另外, 激发态几何相对于基态几何没有发生太大的变化, 这与实验上所观察到的较小斯托克斯频移现象一致.     

MX2(AsH3)2(M=Pd,Pt;X=Cl,Br,I)的含时密度泛函理论研究

采用密度泛函方法(B3LYP)优化了MX2(AsH3)2[M=Pd；X=Cl(1)，Br(2)，I(3)和M=Pt；X=Cl(4)，Br(5)，I(6)]的基态结构，得到的几何参数与实验结果符合．以基态几何为基础，将TD-DFT方法用于计算标题配合物的电子吸收光谱．研究结果表明，金属的dx2-y2与配体所组成的反键轨道为LUMO轨道，从而该类配合物具有d-d跃迁属性的吸收带；在多数跃迁过程中，配体也有较大的贡献．     

Formation, reactivity, and photorelease of metal bound nitrosyl in [Ru(trpy)(L)(NO)](n+) (trpy = 2,2':6',2'-terpyridine, L = 2-phenylimidazo[4,5-f]1,10-phenanthroline)

Nitrosyl complexes with {Ru-NO} (6) and {Ru-NO} (7) configurations have been isolated in the framework of [Ru(trpy)(L)(NO)] ( n+ ) [trpy = 2,2':6',2'-terpyridine, L = 2-phenylimidazo[4,5- f]1,10-phenanthroline] as the perchlorate salts [ 4](ClO 4) 3 and [ 4](ClO 4) 2, respectively. Single crystals of protonated material [ 4-H (+)](ClO 4) 4.2H 2O reveal a Ru-N-O bond angle of 176.1(7) degrees and triply bonded N-O with a 1.127(9) A bond length. Structures were also determined for precursor compounds of [ 4] (3+) in the form of [Ru(trpy)(L)(Cl)](ClO 4).4.5H 2O and [Ru(trpy)(L-H)(CH 3CN)](ClO 4) 3.H 2O. In agreement with largely NO centered reduction, a sizable shift in nu(NO) frequency was observed on moving from [ 4] (3+) (1953 cm (-1)) to [ 4] (2+) (1654 cm (-1)). The Ru (II)-NO* in isolated or electrogenerated [ 4] (2+) exhibits an EPR spectrum with g 1 = 2.020, g 2 = 1.995, and g 3 = 1.884 in CH 3CN at 110 K, reflecting partial metal contribution to the singly occupied molecular orbital (SOMO); (14)N (NO) hyperfine splitting ( A 2 = 30 G) was also observed. The plot of nu(NO) versus E degrees ({RuNO} (6) --> {RuNO} (7)) for 12 analogous complexes [Ru(trpy)(L')(NO)] ( n+ ) exhibits a linear trend. The electrophilic Ru-NO (+) species [ 4] (3+) is transformed to the corresponding Ru-NO 2 (-) system in the presence of OH (-) with k = 2.02 x 10 (-4) s (-1) at 303 K. In the presence of a steady flow of dioxygen gas, the Ru (II)-NO* state in [ 4] (2+) oxidizes to [ 4] (3+) through an associatively activated pathway (Delta S++ = -190.4 J K (-1) M (-1)) with a rate constant ( k [s (-1)]) of 5.33 x 10 (-3). On irradiation with light (Xe lamp), the acetonitrile solution of paramagnetic [Ru(trpy)(L)(NO)] (2+) ([ 4] (2+)) undergoes facile photorelease of NO ( k NO = 2.0 x 10 (-1) min (-1) and t 1/2 approximately 3.5 min) with the concomitant formation of the solvate [Ru (II)(trpy)(L)(CH 3CN)] (2+) [ 2'] (2+). The photoreleased NO can be trapped as an Mb-NO adduct.     

Isomeric complexes of [RuII(trpy)(L)Cl] (trpy=2,2':6',2'-terpyridine and HL=quinaldic acid): preference of isomeric structural form in catalytic chemoselective epoxidation process

The present work deals with the isomeric complexes of the molecular composition [Ru(II)(trpy)(L)Cl] in 1 and 2 (trpy = 2,2':6',2'-terpyridine, L = deprotonated form of quinaldic acid, HL). Isomeric identities of 1 and 2 have been established by their single-crystal X-ray structures, which reveal that under the meridional configuration of trpy, O(-) and N donors of the unsymmetrical L are in trans, cis and cis, trans configurations, respectively, with respect to the Ru-Cl bond. Compounds 1 and 2 exhibit appreciable differences in bond distances involving Ru-Cl and Ru-O1/Ru-N1 associated with L on the basis of their isomeric structural features. In relation to isomer 2, the isomeric complex 1 exhibits a slightly lower Ru(II)-Ru(III) oxidation potential [0.35 (1), 0.38 (2) V versus SCE in CH(3)CN] as well as lower energy MLCT transitions [559 nm and 417 nm (1) and 533 nm and 378 nm (2)]. This has also been reflected in the DFT calculation where a lower HOMO-LUMO gap of 2.59 eV in 1 compared to 2.71 eV in 2 is found. The isomeric structural effect in 1 and 2 has also been prominent in their (1)H NMR spectral profiles. The relatively longer Ru-Cl bond in 1 (2.408(2) ?) as compared to 2 (2.3813(9) ?) due to the trans effect of the anionic O(-) of coordinated L makes it labile, which in turn facilitates the transformation of [Ru(II)(trpy)(L)(Cl)] (1) to the solvate species, [Ru(II)(trpy)(L)(CH(3)CN)](Cl) (1a) while crystallizing 1 from the coordinating CH(3)CN solvent. The formation of 1a has been authenticated by its single-crystal X-ray structure. However, no such exchange of "Cl(-)" by the solvent molecule occurs in 2 during the crystallization process from the coordinating CH(3)CN solvent. The labile Ru-Cl bond in 1 makes it a much superior precatalyst for the epoxidation of alkene functionalities. Compound 1 is found to function as an excellent precatalyst for the epoxidation of a wide variety of alkene functionalities under environmentally benign conditions using H(2)O(2) as an oxidant and EtOH as a solvent, while isomer 2 remains almost ineffective under identical reaction conditions. The remarkable differences in catalytic performances of 1 and 2 based on their isomeric structural aspects have been addressed.     

四齿配体[Ru(iph)(L)2]2+ (L=cpy,mpy, npy)配合物的结构和光谱特征

采用密度泛函的B3LYP和UB3LYP方法分别优化了一系列[Ru(iph)(L)₂]²⁺ (L=cpy (1), mpy (2), npy (3); 其中iph为2,9-双(1′-甲基-2′-咪唑)-1,10-邻二氮杂菲, cpy为4-氰基嘧啶, mpy为4-甲基嘧啶, npy为4-氮二甲基嘧啶)配合物的基态和激发态结构. 利用含时密度泛函理论(TD-DFT)方法, 结合极化连续介质(PCM)模型计算了它们在丙酮溶液中的吸收和发射光谱. 研究结果表明: 优化得到的几何结构参数和相应的实验值符合得非常好. 1和2的最高占据分子轨道主要由金属的d轨道和iph配体的π轨道构成, 但是3主要占据在npy配体上, 而它们的最低空轨道主要由iph配体的π反键轨道占据. 因此, 1和2的最低能吸收和发射属于金属到配体(MLCT)和配体内部(ILCT)的电荷转移跃迁, 而3属于两个配体之间的电荷转移(LLCT)跃迁. 三个配合物的最低能吸收分别在509 nm (1), 527 nm (2)和563 nm (3), 其磷光发射分别在683 nm (1), 852 nm (2)和757 nm (3). 这显示出通过调节L配体的π电子给予能力可以改变最低能吸收和发射的跃迁性质和发光颜色.     

Theoretical studies on the electronic structures and spectroscopic properties for a series of Osmium(II)-2,2′,6′,2′′-terpyridine complexes

A series of Osmium(II) complexes [Os (trpy-R)₂]²⁺(trpy=2,2′,6′,2′′-terpyridine and R=H (1), OH (2), and C₆H₅(3)) have been investigated by the density functional (DF) and ab initio calculations. The structures of 1–3 in the ground and excited states were fully optimized at the B3LYP and CIS level, respectively, and their absorption and emission spectra in the acetonitrile solution were obtained using the TD-DFT (B3LYP) method associated with the PCM model. The calculations indicated that, for 1–3, the variation of the substituents on the terpyridine ligand only slightly changes their geometrical structures in the ground and excited states but leads to a sizable difference in the electronic structures. The results show that the low-lying MLCT/ILCT transitions (at 446 (1), 465 (2), and 499 nm (3)) are red-shifted according to the electron-donating ability of substituents on the terpyridine ligand, but blue-shift trend of the high-lying ILCT transitions (at 301 (1), 297 (2), and 272 nm (3)). It also reveals that the lowest energy emissions of 1–3 at 649 nm, 656 nm, and 676 nm have the character of mixing ³[π*(trpy) → d(Os)] and ³ ππ* (³MLCT/³ILCT) transitions localized on the terpyridine ligand, which are identical to the transition properties of the lowest-energy absorptions.     

Synthesis, carbohydrate- and DNA-binding studies of cationic 2,2':6',2'-terpyridineplatinum(II) complexes containing N- and S-donor boronic acid ligands

A series of platinum(II) complexes of the type [Pt(trpy)L](NO(3))(n) (L = 3- or 4-pyridineboronic acid (3- or 4-pyB, respectively), n = 2; HL = 4-mercaptophenylboronic acid (HmpB), n = 1; trpy = 2,2':6',2'-terpyridine) and [{Pt(trpy)}(2)(μ-pzB)](NO(3))(3) (HpzB = 4-pyrazoleboronic acid) were synthesized and fully characterized by means of multinuclear ((1)H, (13)C, (11)B, and (195)Pt) 1D- and 2D-NMR spectroscopy and elemental analysis. The triflate derivatives [Pt(trpy)(4-pyB)](OTf)(2) and [{Pt(trpy)}(2)(μ-pzB)](OTf)(3) were also prepared, and their molecular structures were confirmed by X-ray crystallography. Variable pH (1)H NMR spectroscopy showed that hydroxylation of the boronic acid group occurs in aqueous solution at pH > 5 and the pK(a) values for the complexes were determined. In buffered aqueous solution (pH 7.4), the complexes bind strongly to simple diols such as catechol and monosaccharides including D-fructose, D-ribose, D-sorbitol and D-mannitol, as determined by isothermal titration calorimetry (ITC). The equilibrium binding constants for these reactions were determined and were found to exceed those of organic boronic acids such as phenylboronic acid by an order of magnitude or greater, an effect that can be directly attributed to the cationic charge of the complexes. 2D-NMR methods (HSQC and HMBC) were used to elucidate the structures of the carbohydrate adducts [Pt(trpy)(3-pyB)]·D-fructose·NO(3) and [Pt(trpy)(4-pyB)]·D-fructose·NO(3) in aqueous solution. DNA-binding experiments with calf-thymus DNA (CT-DNA) indicate an avid DNA-binding interaction by the mononuclear complexes, as determined using thermal melting methods and ITC, but the behaviour of the dinuclear species [{Pt(trpy)}(2)(μ-pzB)](NO(3))(3) is complicated and could not be modeled adequately; higher ionic strength solutions and lower temperatures resulted in a similar DNA binding interaction to the mononuclear complexes. The presence of excess d-fructose did not significantly affect the binding of the platinum(II)-trpy complexes to CT-DNA.     

Theoretical insight into electronic structures and spectroscopic properties of [Pt2(pop)4]4-, [Pt2(pcp)4]4-, and related derivatives (pop = P2O5H2(2-) and pcp = P2O4CH4(2-))

The structures of [Pt2(pop)4]4-, [Pt2(pcp)4]4-, and related species [Pt2(pop)4X2]4- and [Pt2(pop)4]2- in the ground states (pop = P2O5H2(2-), pcp = P2O4CH4(2-), and X = I, Br, and Cl) were optimized using the second-order M?ller-Plesset perturbation (MP2) method. It is shown that the Pt-Pt distances decrease in going from [Pt2(pop)4]4- to [Pt2(pop)4X2]4- to [Pt2(pop)4]2-. This is supported by the analyses of their electronic structures. The calculated aqueous absorption spectra at the time-dependent density functional theory (TD-DFT) level agree with experimental observations. The unrestricted MP2 method was employed to optimize the structures of [Pt2(pop)4]4- and [Pt2(pcp)4]4- in the lowest-energy triplet excited states. The Pt-Pt contraction trend is well reproduced in these calculations. For [Pt2(pop)4]4-, the Pt-Pt distance decreases from 2.905 A in the ground state to 2.747 A in the excited state, which is comparable to experimental values of 2.91-2.92 A and 2.64-2.71 A, respectively. On the basis of the excited-state structures of such complexes, TD-DFT predicts the solution emissions at 480 and 496 nm, which is closer to the experimental values of 512 and 510 nm emissions, respectively.     

Syntheses, luminescence behavior, and assembly reaction of tetraalkynylplatinate(II) complexes: crystal structures of [Pt((t)Bu(3)trpy)(Ctbd1;CC(5)H(4)N)Pt((t)Bu(3)trpy)](PF(6))(3) and [Pt(2)Ag(4)(Ctbd1;CCtbd1;CC(6)H(4)CH(3)-4)(8)(THF)(4)

A series of tetraalkynylplatinate(II) complexes, (NBu(4))(2)[Pt(Ctbd1;CR)(4)] (R = C(6)H(4)N-4, C(6)H(4)N-3, and C(6)H(3)N(2)-5), and the diynyl analogues, (NBu(4))(2)[Pt(Ctbd1;CCtbd1;CR)(4)] (R = C(6)H(5) and C(6)H(4)CH(3)-4), have been synthesized. These complexes displayed intense photoluminescence, which was assigned as metal-to-ligand charge transfer (MLCT) transitions. Reaction of (Bu(4)N)(2)[Pt(Ctbd1;CC(5)H(4)N-4)(4)] with 4 equiv of [Pt((t)Bu(3)trpy)(MeCN)](OTf)(2) in methanol did not yield the expected pentanuclear platinum product, [Pt(Ctbd1;CC(5)H(4)N)(4)[Pt((t)Bu(3)trpy)](4)](OTf)(6), but instead afforded a strongly luminescent 4-ethynylpyridine-bridged dinuclear complex, [Pt((t)Bu(3)trpy)(Ctbd1;CC(5)H(4)N)Pt((t)Bu(3)trpy)](PF(6))(3,) which has been structurally characterized. The emission origin is assigned as derived from states of predominantly (3)MLCT [d(pi)(Pt) --> pi((t)Bu(3)trpy)] character, probably mixed with some intraligand (3)IL [pi --> pi(Ctbd1;C)], and ligand-to-ligand charge transfer (3)LLCT [pi(Ctbd1;C) --> pi((t)()Bu(3)trpy)] character. On the other hand, reaction of (Bu(4)N)(2)[Pt(Ctbd1;CCtbd1;CC(6)H(4)CH(3)-4)(4)] with [Ag(MeCN)(4)][BF(4)] gave a mixed-metal aggregate, [Pt(2)Ag(4)(Ctbd1;CCtbd1;CC(6)H(4)CH(3)-4)(8)(THF)(4)]. The crystal structure of [Pt(2)Ag(4)(Ctbd1;CCtbd1;CC(6)H(4)CH(3)-4)(8)(THF)(4)] has also been determined. A comparison study of the spectroscopic properties of the hexanuclear platinum-silver complex with its precursor complex has been made and their spectroscopic origins were suggested.     

两种金属钌配合物异构体紫外-可见吸收光谱的理论计算

在B3LYP/LANL2DZ水平上优化了[(trpy)(pic)RuCl] (pic是皮考林离子; trpy为2,2’,2"-联三吡啶)顺反两种异构体的结构, 并用含时密度泛函方法(TD-DFT)计算了它们在乙腈溶液中的吸收光谱. 计算表明它们在可见光区都有较强的宽吸收带, 它们在可见光区吸收峰的位置分别为510.2和383.2, 522.5和398.4 nm处, 计算和实验结果在吸收峰的位置和相对强度上都是非常吻合的. 两种异构体的最低能量吸收带都具有MLCT/ILCT/LLCT性质, 在它们的配体上引入—COOH等极性基团则可能用于太阳光伏电池的光敏化剂.     

联吡啶钌配合物[Ru(Htcterpy)X3]3-[X=NCS,CN,Cl]的电子结构和光谱性质的理论研究

利用DFT中的B3LYP方法优化了3个联吡啶钌配合物[Ru(Htcterpy)X3]3-[tcterpy=4,4',4"-tricarboxy-2,2'∶6',2"-terpyridine, X=NCS(1), CN(2), Cl(3)]的基态几何结构, 得到的几何参数与实验结果吻合得很好. 采用TD-DFT方法, 得到了配合物1~3在气态和溶液(乙醇溶液和水溶液)中的激发态电子结构和电子吸收光谱. 利用SCRF方法中的CPCM模型来模拟溶剂化效应. 研究结果表明, 配合物1~3在气态和溶液中的吸收跃迁性质相似, 低能吸收均被指认为MLCT和LLCT的混合跃迁, 高能吸收均被指认为三联吡啶配体内的π→π*跃迁. 溶剂化效应使配合物1~3在溶液中的吸收光谱蓝移.     

Switching between ligand-to-ligand charge-transfer, intraligand charge-transfer, and metal-to-ligand charge-transfer excited states in platinum(II) terpyridyl acetylide complexes induced by pH change and metal ions

A series of platinum(II) terpyridyl alkynyl complexes, [Pt{4'-(4-R1-C6H4)terpy}(C[triple chemical bond]C-C6H4-R(2)-4)]ClO4 (terpy=2,2':6',2'-terpyridyl; R1=R2=N(CH3)2 (1); R1=N(CH3)2, R2=N-[15]monoazacrown-5 (2); R1=CH3, R2=N(CH3)2 (3); R1=N(CH3)2, R2=H (4); R1=CH3, R2=H (5)), has been synthesized and the photophysical properties of the complexes have been examined through measurement of their UV/Vis absorption spectra, photoluminescence spectra, and transient absorptions. Complex 3 shows a lowest-energy absorption corresponding to a ligand-to-ligand charge-transfer (LLCT) transition from the acetylide to the terpyridyl ligand, whereas 4 shows an intraligand charge-transfer (ILCT) transition from the pi orbital of the 4'-phenyl group to the pi* orbital of the terpyridyl. Upon protonation of the amino groups in 3 and 4, their lowest-energy excited states are switched to dpi(Pt)-->pi*(terpy) metal-to-ligand charge-transfer (MLCT) states. The lowest-energy absorption for 1 and 2 may be attributed to an LLCT transition from the acetylide to the terpyridyl. Upon addition of an acid to a solution of 1 or 2, the amino group on the acetylide is protonated first, followed by the amino group on the terpyridyl. Thus, the lowest excited state of 1 and 2 can be successively switched from the LLCT state to the ILCT state and then to the MLCT state by controlling the amount of the acid added. Such switches in the excited state are fully reversible upon subsequent addition of a base to the solution. Sequential addition of alkali metal or alkaline earth metal ions and then an acid to a solution of 2 also leads to switching of its lowest excited state from the LLCT state, first to the ILCT state and then to the MLCT state. All of the complexes exhibit a transient absorption of the terpyridyl anion radical, which is present in all of the LLCT, ILCT, and MLCT states. However, the shape of the transient absorption spectrum depends on both the substitution pattern on the terpyridyl moiety and the nature of the excited state.     

[M(N)X2]-(M=Ru, Os; X=S2C6H4, mnt)的电子结构和光谱性质的理论研究

利用密度泛函理论(DFT)中的B3LYP方法优化了氮化钌和氮化锇配合物[M(N)X2]-[M=Ru, Os; X=S2C6H4, mnt(maleonitriledithiolate)]的基态几何结构, 得到的几何参数与实验结果吻合得很好. 采用TD-DFT方法, 得到了配合物在CH3CN溶液中的激发态电子结构和电子吸收光谱. 利用SCRF方法中的CPCM模型来模拟溶剂化效应. 研究结果表明, 配合物1~4在CH3CN溶液中的吸收跃迁性质相似, 低能吸收均被指认为LMCT和LLCT的混合跃迁, 高能吸收均被指认为ILCT/LLCT跃迁.