一种新型苝酰亚胺的合成及其与C60之间的电荷转移作用

设计和合成了一种新型苝酰亚胺电子受体—N,N ′-二嘧啶基苝四羧基二酰亚胺(DMP), 利用傅里叶红外光谱和元素分析表征了DMP的分子结构. 通过与N,N ′-二苯基-3,4,9,10-苝四羧基二酰亚胺(DPP)的循环伏安实验的对比, 证明了嘧啶基的引入降低了分子的LUMO能级. 研究了DMP与C₆₀层-层蒸镀(layer-by-layer evaporation)薄膜的荧光变化, 确认其界面处发生了由于能级位置差异导致的电荷转移.     

芳氧基取代酞菁锌的合成及光物理化学性质

合成得到3-(5-氨基-萘氧基)邻苯二甲腈(C18H11N3O)、4-(5-氨基-萘氧基)邻苯二甲腈(C18H11N3O)、3-联苯氧基邻苯二甲腈(C20H12N2O)及4-联苯氧基邻苯二甲腈(C20H12N2O)4种未见报导的取代邻苯二甲腈,以此为前躯体合成了四[α-(5-氨基-萘氧基)]酞菁锌(C72H44N12O4Zn)、四[β-(5-氨基-萘氧基)]酞菁锌(C72H44N12O4Zn)、四[α-(联苯氧基)]酞菁锌(C80H48N8O4Zn)和四[β-(联苯氧基)]酞菁锌(C80H48N8O4Zn)4种未见报导的芳氧基取代酞菁锌配合物。通过测定它们的紫外-可见吸收光谱、荧光发射光谱,获得其最大吸收波长及其摩尔消光系数、最大发射波长、荧光量子产率(ΦF)、单线态氧量子产率(ΦΔ)及光降解速率常数并与其类似物进行了比较,探讨了它们的光物理光化学性质的构效关系。研究结果表明四[α-(联苯氧基)]酞菁锌在红光区具有大的摩尔消光系数,且具有较高的ΦΔ,有望开发成为光动力治疗用光敏剂。     

氟代⊥酰亚胺掺杂PVK薄膜的结构特性和光电导性能

采用一种新型的有机电子受体 N,N′-二 (五氟代苯基 ) - 3,4 ,9,10 -⊥四羧基二酰亚胺(DFPP) ,与空穴传输材料聚乙烯基咔唑 (PVK)掺杂复合 ,制备了单层有机光电导体 ,发现无论是在充正电还是在充负电情况下 ,该复合光电导体均表现出十分优异的光电导性能。结合 DSC、UV- Vis吸收、XPS和循环伏安等测试手段研究了 DFPP掺杂的 PVK薄膜的凝聚态、光学和电学性质 ,发现 DFPP与PVK形成了给体 -受体 (D- A)复合物 ,而且 DFPP分子可在薄膜中形成电子传输通道 ,由此使 DFPP掺杂 PVK薄膜具有高的光致激子分离效率和良好的电子传输能力     

氟代苝酰亚胺掺杂PVK薄膜的结构特性和光电导性能

采用一种新型的有机电子受体N，N’-二(五氟代苯基)-3，4，9，10-菲四羧基二酰亚胺(DFPP)．与空穴传输材料聚乙烯基咔唑(PVK)掺杂复合．制备了单层有机光电导体．发现无论是在充正电还是在充负电情况下．该复合光电导体均表现出十分优异的光电导性能。结合DSC、UV—Vis吸收、XPS和循环伏安等测试手段研究了DFPP掺杂的PVK薄膜的凝聚态、光学和电学性质．发现DFPP与PVK形成了给体-受体(D—A)复合物，而且DFPP分子可在薄膜中形成电子传输通通道，由此使DFPP掺杂PVK薄膜具有高的光致激子分离效率和良好的电子传输能力。     

基于PCPDTBT复合材料的制备及光致电荷转移

合成了PCPDTBT,通过NMR,GPC等方法对聚合物进行了表征.研究了聚合物的热学与电化学性质.采用溶液法将电子给体PCPDTBT与两种电子受体1-(3-甲氧基羰基)丙基-1-苯基[6,6]C61(PCBM)和ZnO纳米粒子分别进行了复合,通过研究复合前后的荧光变化,确认了给体-受体两相界面间发生了由分子能级差引发的光致电荷转移.这些研究结果为探索性能更佳的有机太阳能电池材料体系提供了重要的参考依据.     

以二苯甲酮为端基的第一代树状取代酞菁锌的合成

4-甲基二苯甲酮经N-溴代丁二酰亚胺溴代制得4-溴甲基二苯甲酮(1);1与3,5-二羟基苯甲醇反应合成了外围带有二苯甲酮取代基的第一代树枝状分子3,5-二(二苯甲酮-4-甲氧基)苯甲醇(2);2与4-硝基邻苯二甲腈缩合制得外围带有二苯甲酮取代基的第一代树枝状分子4-[3,5-二(二苯甲酮-4-甲氧基)苯甲氧基]邻苯二甲腈(3);3经"液相法"环合生成外围带有二苯甲酮取代基的第一代树枝状分子取代的酞菁锌配合物——四[3,5-二(二苯甲酮-4-甲氧基)苯甲氧基]锌酞菁[ZnPc(C35H27O5)4],其结构经UV,1HNMR,IR和MS表征。     

具有Frétchet树枝结构的新型酞菁锌(Ⅱ)配合物:四-{3,5-二-[3,5-二-(4-羧基苯甲氧基)苯甲氧基]-苯甲氧基}酞菁锌(Ⅱ)的合成与表征

报道了一种新型Frétchet树枝配体取代酞菁锌(II)配合物:四-{3,5-二-[3,5-二-(4-羧基苯甲氧基)苯甲氧基]-苯甲氧基}酞菁锌(II)的合成与表征.首先将对氰基苄溴与3,5-二羟基苯甲醇通过Frétchet反应合成3,5-[二-(4-氰基苯甲氧基)]苯甲醇(1),1与四溴化碳和三苯基膦在四氢呋喃中反应合成3,5-二-(4-氰基苯甲氧基)苄溴(2),2与3,5-二羟基苯甲醇反应合成3,5-二-[3,5-二-(4-氰基苯甲氧基)苯甲氧基]苯甲醇(3),接着,3与4-硝基邻苯二甲腈合成"前驱物"四-{3,5-[二-(4-氰基苯甲氧基)]}苯甲氧基邻苯二甲腈(4),然后以1,8-二氮杂双环[5.4.0]十一碳-7-烯(DBU)为催化剂,醋酸锌为模板剂,4通过缩聚反应合成氰基端基的Frétchet树枝配体取代酞菁锌四-{3,5-二-[3,5-二-(4-氰基苯甲氧基)苯甲氧基]-苯甲氧基}锌酞菁配合物5,最后,5的氰基端基在NaOH溶液中水解为相应的以羧基端基Frétchet树枝配体取代酞菁锌:四-{3,5-二-[3,5-二-(4-羧基苯甲氧基)苯甲氧基]-苯甲氧基}酞菁锌(II)(6).采用元素分析,IR,1H NMR,ESI-MS和MALDI-TOF-MS表征所有化合物的结构,通过UV/Vis,稳态和瞬态荧光光谱法研究了5和6的光物理性质.5和6是一类性能较好的树枝状酞菁光敏剂.     

萘二酰亚胺类电子受体材料分子设计与开路电压的理论调控

采用密度泛函理论预测了6个萘二酰亚胺(NDI)衍生物电子受体分子An(n=1~6)的几何构型、前线轨道特征及吸收光谱,并分别与选定的3个给体分子Dm(m=1~3)组合,构建给-受体(D-A)界面,从单分子尺度评估了不同D-A界面载流子的复合程度.结果表明,引入N、O、S等杂原子可以改变分子间氢键位点及强度,调节D-A界面分子间的距离与位移,以降低界面载流子复合,通过减小光电压损失获得高的开路电压V_(oc);此外,通过计算给体HOMO~D与受体LUMO~A之间的电子耦合V_(if)发现,平面性均较好的D-A分子组合V_(if)较大,界面载流子易于复合,会引起较大的光电压损失,不利于获得高的V_(oc).将平面性好的受体与非平面型给体材料搭配作为有机太阳能电池光活性层有可能获得高的V_(oc).综合考虑ΔE_L、V_(if)、D-A分子的平面性和光吸收效率等因素,认为D3-A5组合有望成为电子迁移率高、可见光和近红外区吸收宽、界面激子能有效分离且不易复合的理想给-受体分子组合对.     

磺化2,3-萘酞菁锌(Ⅱ)、钴(Ⅱ)的电子吸收光谱和荧光光谱的研究

研究了磺化2，3-萘酞菁锌(Ⅱ)、钴(Ⅱ)在DMF(N，N-二甲基甲酰胺)、DMSO(二甲基亚砜)、乙醇、水等溶剂中的电子吸收光谱和荧光光谱．萘酞菁配合物的Q带与相应的酞菁配合物Q带相比，电子吸收光谱红移80～90nm，荧光光谱红移约100nm，荧光强度也显增加．在金属萘酞菁中引入磺酸基，配合物的电子吸收光谱Q带发生红移，但是影响不大、对于相同中心金属的配合物，改变溶剂的种类对配合物的电子吸收光谱的Q带影响较大．在金属萘酞菁环上引入一个磺酸基时，在相同溶剂中与无取代萘酞菁相比发生荧光光谱Q带红移，荧光强度增大．但在萘酞菁环上继续引入磺酸基时，荧光强度反而减少．磺化萘酞菁钴比磺化萘酞菁锌有较大的荧光强度．不同浓度下的电子吸收光谱和荧光光谱说明金属萘酞菁有集聚倾向、能形成基激缔合物．     

新型酞菁-苝分子异质结的合成及其光伏性能研究

通过酰胺键将酞菁(电子给体单元)和苝二酰亚胺(电子受体单元)偶联,合成了新型的酞菁-苝分子异质结,其在二氯甲烷、氯仿、四氢呋喃等常用溶剂中有较好的溶解度.紫外光谱分析表明其吸收光谱是酞菁和苝二酰亚胺信号的叠加,出现在300～780 nm之间.该分子摩尔消光系数高达105L mol-1 cm-1数量级,说明具有较宽的太阳光谱覆盖范围和很高的吸光系数.基于这些良好的光谱响应特性,制备了以该分子与[6,6]-苯基-C61-丁酸酸甲酯(PC61BM)为光活性层的有机太阳能电池(OSCs),该电池器件结构为ITO/聚(3,4-乙撑二氧噻吩):聚苯乙烯磺酸(PEDOT:PSS)/酞菁-苝给受体分子:PC61BM/Ca/Al,光电转换效率(PCE)为0.009%,对应的开路电压(Voc)为0.472 V,短路电流(Jsc)为0.104 mA/cm2,填充因子(FF)为0.18.     

Light harvesting zinc naphthalocyanine-perylenediimide supramolecular dyads: long-lived charge-separated states in nonpolar media

Photoinduced electron-transfer dynamics of self-assembled donor-acceptor dyads formed by axial coordination of zinc naphthalocyanine, ZnNc, and perylenediimide (PDI) bearing either pyridine (py) or imidazole (im) coordinating ligands were investigated. The PDIim unit was functionalized with tert-octylphenoxy groups at the bay positions, which avoid aggregation providing solubility, to examine the effect of the bulky substituents at the bay positions on the rates of electron-transfer reactions. The combination between zinc naphthalocyanine and perylenediimide entities absorbs light over a wide region of the visible and near infrared (NIR) spectrum. The binding constants of the self-assembled ZnNc:PDIpy (1) and ZnNc:PDIim (2) in toluene were found to be 2.40 × 10(4) and 1.10 × 10(5) M(-1), respectively, from the steady-state absorption and emission measurements, indicating formation of moderately stable complexes. The geometric and electronic calculations by using an ab initio B3LYP/6-311G method showed the majority of the highest occupied frontier molecular orbital (HOMO) on the zinc naphthalocyanine entity, while the lowest unoccupied molecular orbital (LUMO) was on the perylenediimide entities, suggesting that the charge-separated states of the supramolecular dyads are ZnNc˙(+):PDI˙(-). The electrochemical results suggest the exothermic charge-separation process via the singlet states of both ZnNc and PDI entities in nonpolar toluene. Upon coordination of perylenediimide to ZnNc, the main quenching pathway involved charge separation via the singlet-excited states of ZnNc and PDIs. Clear evidence of the intramolecular electron transfer from the singlet-excited state of ZnNc to PDI within the supramolecular dyads in toluene was monitored by the femtosecond laser photolysis by observing the characteristic absorption band of the PDI radical anion (PDI˙(-)) and the ZnNc radical cation (ZnNc˙(+)) in the visible and NIR regions. The rate constants of charge-separation (k(CS)) processes of the self-assembled dyads 1 and 2 were determined to be 4.05 × 10(10) and 1.20 × 10(9) s(-1), respectively. The rate constant of charge recombination (k(CR)) and the lifetime of charge-separated states (τ(CS)) of dyad 1 were determined to be 2.34 × 10(8) s(-1) and 4.30 ns, respectively. Interestingly, a slower charge recombination (2.20 × 10(7) s(-1)) and a longer lifetime of the charge separated state (45 ns) were observed in dyad 2 in nonpolar toluene by utilizing the nanosecond transient measurements. The absorption in a wide section of the solar spectrum and the high charge-separation/charge-recombination ratio suggest the usefulness of the self-assembled zinc naphthalocyanine-perylenediimide dyads as good photosynthetic models.     

Photoinduced Electron Transfer in Zinc Naphthalocyanine–Naphthalenediimide Supramolecular Dyads

Photoinduced electron transfer was studied in self‐assembled donor–acceptor dyads, formed by axial coordination of pyridine appended with naphthalenediimide (NDI) to zinc naphthalocyanine (ZnNc). The NDI‐py:ZnNc ( 1 ) and NDI(CH₂)₂‐py:ZnNc ( 2 ) self‐assembled dyads absorb light over a wide region of the UV/Vis/near infrared (NIR) spectrum. The formation constants of the dyads 1 and 2 in toluene were found to be 2.5×10⁴ and 2.2×10⁴ M ^?1, respectively, from the steady‐state absorption and emission measurements, suggesting moderately stable complex formation. Fluorescence quenching was observed upon the coordination of the pyridine‐appended NDI to ZnNc in toluene. The energy‐level diagram derived from electrochemical and optical data suggests that exergonic charge separation through the singlet state of ZnNc (¹ZnNc*) provides the main quenching pathway. Clear evidence for charge separation from the singlet state of ZnNc to NDI was provided by femtosecond laser photolysis measurements of the characteristic absorption bands of the ZnNc radical cation in the NIR region at 960 nm and the NDI radical anion in the visible region. The rates of charge‐separation of 1 and 2 were found to be 2.2×10¹⁰ and 4.4×10⁹ s^?1, respectively, indicating fast and efficient charge separation (CS). The rates of charge recombination (CR) and the lifetimes of the charge‐separated states were found to be 8.50×10⁸ s^?1 (1.2 ns) for 1 and 1.90×10⁸ s^?1 (5.3 ns) for 2 . These values indicate that the rates of the CS and CR processes decrease as the length of the spacer increases. Their absorption over a wide portion of the solar spectrum and the high ratio of the CS/CR rates suggests that the self‐assembled NDI‐py:ZnNc and NDI(CH₂)₂‐py:ZnNc dyads are useful as photosynthetic models.     

Probing ruthenium-acetylide bonding interactions: synthesis, electrochemistry, and spectroscopic studies of acetylide-ruthenium complexes supported by tetradentate macrocyclic amine and diphosphine ligands

The synthesis and spectroscopic properties of trans-[RuL4(C[triple bond]CAr)2] (L4 = two 1,2-bis(dimethylphosphino)ethane, (dmpe)2; 1,5,9,13-tetramethyl-1,5,9,13-tetraazacyclohexadecane, 16-TMC; 1,12-dimethyl-3,4:9,10-dibenzo-1,12-diaza-5,8-dioxacyclopentadecane, N2O2) are described. Investigations into the effects of varying the [RuL4] core, acetylide ligands, and acetylide chain length for the [(-)C[triple bond]C(C6H4C[triple bond]C)(n-1)Ph] and [(-)C[triple bond]C(C6H4)(n-1)Ph] (n = 1-3) series upon the electronic and electrochemical characteristics of trans-[RuL4(C[triple bond]CAr)2](0/+) are presented. DFT and TD-DFT calculations have been performed on trans-[Ru(L')4(C[triple bond]CAr)2](0/+) (L' = PH3 and NH3) to examine the metal-acetylide pi-interaction and the nature of the associated electronic transition(s). It was observed that (1) the relationship between the transition energy and 1/n for trans-[Ru(dmpe)2{C[triple bond]C(C6H4C[triple bond]C)(n-1)Ph}2] (n = 1-3) is linear, and (2) the sum of the d(pi)(Ru(II)) --> pi*(C[triple bond]CAr) MLCT energy for trans-[Ru(16-TMC or N2O2)(C[triple bond]CAr)2] and the pi(C[triple bond]CAr) --> d(pi)(Ru(III)) LMCT energy for trans-[Ru(16-TMC or N2O2)(C[triple bond]CAr)2]+ corresponds to the intraligand pi pi* absorption energy for trans-[Ru(16-TMC or N2O2)(C[triple bond]CAr)2]. The crystal structure of trans-[Ru(dmpe)2{C[triple bond]C(C6H4C[triple bond]C)2Ph}2] shows that the two edges of the molecule are separated by 41.7 A. The electrochemical and spectroscopic properties of these complexes can be systematically tuned by modifying L4 and Ar to give E(1/2) values for oxidation of trans-[RuL4(C[triple bond]CAr)2] that span over 870 mV and lambda(max) values of trans-[RuL4(C[triple bond]CAr)2] that range from 19,230 to 31,750 cm(-1). The overall experimental findings suggest that the pi-back-bonding interaction in trans-[RuL4(C[triple bond]CAr)2] is weak and the [RuL4] moiety in these molecules may be considered to be playing a "dopant" role in a linear rigid pi-conjugated rod.     

Synthesis of a novel ionic liquid containing phosphorus and its application in intumescent flame retardant polypropylene system

A novel ionic liquid containing phosphorus ([PCMIM]Cl) was synthesized and characterized by FTIR, ¹H NMR, ¹³C NMR and ³¹P NMR. Moreover, a new intumescent flame retardant (IFR) system, which was composed of [PCMIM]Cl and ammonium polyphosphate (APP), was used to impart flame retardancy and dripping resistance to polypropylene (PP). The flammability and thermal behaviors of intumescent flame‐retarded PP (PP/IFR) composites were evaluated by limiting oxygen index (LOI), UL‐94 test, thermogravimetric analysis (TGA) and cone calorimeter test. It was found that there was an obvious synergistic effect between [PCMIM]Cl and APP. When the weight ratio of [PCMIM]Cl and APP was 1:5 and the total amount of IFR was kept at 30 wt%, LOI value of PP/IFR composite reached 31.8, and V‐0 rating was obtained. Moreover, both the peak heat release rate and the peak mass loss rate of PP/IFR composites decreased significantly relative to PP and PP/APP composite from cone calorimeter analysis. The TGA curves suggested that [PCMIM]Cl had good ability of char formation, and when combined with APP, it could greatly promote the char formation of PP/IFR composites, hence improved the flame retardancy. Additionally, the rheological behaviors and mechanical properties of PP/IFR composites were also investigated, and it was found that [PCMIM]Cl could also serve as an efficient lubricant and compatibilizer between APP and PP, endowing the materials with satisfying processability and mechanical properties. Copyright © 2013 John Wiley & Sons, Ltd.     

Insertion, reduction, and carbon-carbon coupling induced by monomeric aluminum hydride compounds bearing substituted pyrrolyl ligands

A monomeric aluminum hydride complex bearing substituted pyrrolyl ligands, AlH[C(4)H(3)N(CH(2)NMe(2))-2](2) (1), was synthesized and structurally characterized. To further confirm the presence of Al--H bonds, the compound AlD[C(4)H(3)N(CH(2)NMe(2))-2](2) ([D]1) was synthesized by reacting LiAlD(4) with [C(4)H(4)N(CH(2)NMe(2))-2]. Compound 1 and [D]1 react with phenyl isothiocyanate yielding Al[C(4)H(3)N(CH(2)NMe(2))-2](2)[eta(3)-SCHNPh] (2) and Al[C(4)H(3)N(CH(2)NMe(2))-2](2)[eta(3)-SCDNPh] ([D]2) by insertion. The reactions of 1 with 9-fluorenone and benzophenone generated the unusual aluminum alkoxide complexes 3 and 4, respectively, through intramolecular proton abstraction and C-C coupling. A mechanistic study shows that 9-fluorenone coordinates to [D]1 and releases one equivalent of HD followed by C-C coupling and hydride transfer to yield the final product. Reduction of benzil with 1 affords aluminum enediolate complex 5 in moderate yield. Mechanistic studies also showed that the benzil was inserted into the aluminum hydride bond of [D]1 through hydroalumination followed by proton transfer to generate the final product [D]5. All new complexes have been characterized by (1)H and (13)C NMR spectroscopy and X-ray crystallography.     

Lamellar structure in poly(ala-gly) determined by solid-state NMR and statistical mechanical calculations

Lamellar structure of poly(Ala-Gly) or (AG)n in the solid was examined using 13C solid-state NMR and statistical mechanical approaches. Two doubly labeled versions, [1-13C]Gly14[1-13C]Ala15- and [1-13C]Gly18[1-13C]Ala19 of (AG)15 were examined by two-dimensional (2D) 13C spin diffusion NMR in the solid state. In addition five doubly labeled [15N,13C]-versions of the same peptide, (AG) 15 and 15 versions labeled [3-13C] in each of the successive Ala residues were utilized for REDOR and 13C CP/MAS NMR measurements, respectively. The observed spin diffusion NMR spectra were consistent with a structure containing a combination of distorted beta-turns with a large distribution of the torsion angles and antiparallel beta-sheets. The relative proportion of the distorted beta-turn form was evaluated by examination of 13C CP/MAS NMR spectra of [3-13C]Ala-(AG)15. In addition, REDOR determinations showed five kinds of atomic distances between doubly labeled 13C and 15N nuclei which were also interpreted in terms of a combination of beta-sheets and beta-turns. Our statistical mechanical analysis is in excellent agreement with our Ala Cbeta 13C CP/MAS NMR data strongly suggesting that (AG)15 has a lamellar structure.     

Probing the ruthenium-cumulene bonding interaction: synthesis and spectroscopic studies of vinylidene- and allenylidene-ruthenium complexes supported by tetradentate macrocyclic tertiary amine and comparisons with diphosphine analogues of ruthenium and osmium

The synthesis and spectroscopic properties of trans-[Cl(16-TMC)Ru[double bond]C[double bond]CHR]PF(6) (16-TMC = 1,5,9,13-tetramethyl-1,5,9,13-tetraazacyclohexadecane, R = C(6)H(4)X-4, X = H (1), Cl (2), Me (3), OMe (4); R = CHPh(2) (5)), trans-[Cl(16-TMC)Ru[double bond]C[double bond]C[double bond]C(C(6)H(4)X-4)(2)]PF(6) (X = H (6), Cl (7), Me (8), OMe (9)), and trans-[Cl(dppm)(2)M[double bond]C[double bond]C[double bond]C(C(6)H(4)X-4)(2)]PF(6) (M = Ru, X = H (10), Cl (11), Me (12); M = Os, X = H (13), Cl (14), Me (15)) are described. The crystal structures of 1, 5, 6, and 8 show that the Ru-C(alpha) and C(alpha)-C(beta) distances of the allenylidene complexes fall between those of the vinylidene and acetylide relatives. Two reversible redox couples are observed by cyclic voltammetry for 6-9, with E(1/2) values ranging from -1.19 to -1.42 and 0.49 to 0.70 V vs Cp(2)Fe(+/0), and they are both 0.2-0.3 and 0.1-0.2 V more reducing than those for 10-12 and 13-15, respectively. The UV-vis spectra of the vinylidene complexes 1-4 are dominated by intense high-energy bands at lambda(max) < or = 310 nm (epsilon(max) > or = 10(4) dm(3) mol(-1) cm(-1)), while weak absorptions at lambda(max) > or = 400 nm (epsilon(max) < or = 10(2) dm(3) mol(-1) cm(-1)) are tentatively assigned to d-d transitions. The resonance Raman spectrum of 5 contains a nominal nu(C[double bond]C) stretch mode of the vinylidene ligand at 1629 cm(-1). The electronic absorption spectra of the allenylidene complexes 6-9 exhibit an intense absorption at lambda(max) = 479-513 nm (epsilon(max) = (2-3) x 10(4) dm(3) mol(-1) cm(-1)). Similar electronic absorption bands have been found for 10-12, but the lowest energy dipole-allowed transition is blue-shifted by 1530-1830 cm(-1) for the Os analogues 13-15. Ab initio calculations have been performed on the ground state of trans-[Cl(NH(3))(4)Ru[double bond]C[double bond]C[double bond]CPh(2)](+) at the MP2 level, and imply that the HOMO is not localized purely on the metal center or allenylidene ligand. The absorption band of 6 at lambda(max) = 479 nm has been probed by resonance Raman spectroscopy. Simulations of the absorption band and the resonance Raman intensities show that the nominal nu(C[double bond]C[double bond]C) stretch mode accounts for ca. 50% of the total vibrational reorganization energy, indicating that this absorption band is strongly coupled to the allenylidene moiety. The excited-state reorganization of the allenylidene ligand is accompanied by rearrangement of the Ru[double bond]C and Ru[bond]N (of 16-TMC) fragments, which supports the existence of bonding interaction between the metal and C[double bond]C[double bond]C unit in the electronic excited state.     

Biosynthesis of chaetochromin A, a bis(naphtho-gamma-pyrone), in Chaetomium spp

The biosynthesis of chaetochromin A, a metabolite of Chaetomium gracile, has been studied using [13CH3]methionine, sodium [1-13C]acetate, sodium [1,2-13C2]acetate, sodium [1-13C,2,2,2-2H3]acetate, and sodium [1-13C,1,1-18O2]acetate as precursors. The folding pattern of the polyketide chain in chaetochromin A, biosynthesized from sodium [1,2-13C2]acetate as the precursor, was determined to be the same as that of rubrofusarin by carbon-13 nuclear magnetic resonance (13C-NMR) analysis. By using [13CH3]methionine as a precursor, the source of 2-CH3 was determined. When sodium [1-13C,2,2,2-2H3]acetate was fed, a beta-isotope-shifted peak was observed only for carbon 2. In the 13C-NMR spectra of chaetochromin A and of its hexamethyl ether derived from sodium [1-13C,1,1-18O2]acetate, isotope-shifted peaks were observed for carbons 4, 5, 6, 8 and 10a, but not for carbon 2. These results showed that oxygen 1 originated from the same unit of acetate as carbon 10a.     

螺二芴富勒烯吡咯烷衍生物的合成及电化学和光限幅性能

设计合成了3种新颖的螺二芴键联富勒烯(C₆₀/C₇₀)吡咯烷衍生物, 其结构通过IR, ¹H NMR, ¹³C NMR和MALDI-TOF进行确证, 其电化学性质用循环伏安法进行研究. 结果表明, C₇₀衍生物6的还原电位较C₆₀衍生物7分别向负电势移动0.1, 0.12和0.01 V. 同时, 使用纳秒和飞秒激光分别研究了化合物6, 7和8的光限幅性能, 其光限幅阈值分别为15.3, 23.3和13.7 J/cm², 表明材料具有优异的光限幅性能.     

The economical synthesis of [2'-(13)C, 1,3-(15)N2]uridine; preliminary conformational studies by solid state NMR

The synthesis of [2'-(13)C, 1,3-(15)N2]uridine 11 was achieved as follows. An epimeric mixture of D-[1-(13)C]ribose 3 and D-[1-(13)C]arabinose 4 was obtained in excellent yield by condensation of K13CN with D-erythrose 2 using a modification of the Kiliani-Fischer synthesis. Efficient separation of the two aldose epimers was pivotally achieved by a novel ion-exchange (Sm3+) chromatography method. D-[2-(13)C]Ribose 5 was obtained from D-[1-(13)C]arabinose 4 using a Ni(II) diamine complex (nickel chloride plus TEMED). Combination of these procedures in a general cycling manner can lead to the very efficient preparation of specifically labelled 13C-monosaccharides of particular chirality. 15N-labelling was introduced in the preparation of [2'-(13)C, 1,3-(15)N2]uridine 11 via [15N2]urea. Cross polarisation magic angle spinning (CP-MAS) solid-state NMR experiments using rotational echo double resonance (REDOR) were carried out on crystals of the labelled uridine to show that the inter-atomic distance between C-2' and N-1 is closely similar to that calculated from X-ray crystallographic data. The REDOR method will be used now to determine the conformation of bound substrates in the bacterial nucleoside transporters NupC and NupG.