Tetrameric porphyrin formation of 2‐hydroxymethylpyrrole fused with porphyrins through a bicyclo[2.2.2]octadiene unit gave bicyclo[2.2.2]octadiene‐fused porphyrin pentamers. Thermal conversion of the pentamers gave fully π‐conjugated cruciform porphyrin pentamers fused with benzene units in quantitative yields. UV/Vis spectra of fully π‐conjugated porphyrin pentamers showed one very strong Q absorption and were quite different from those of usual porphyrins. From TD‐DFT calculations, the HOMO level is 0.49 eV higher than the HOMO?1 level. The LUMO and LUMO+1 levels are very close and are lower by more than 0.27 eV than those of other unoccupied MOs. The strong Q absorption was interpreted as two mutually orthogonal single‐electron transitions (683 nm: 86 %, HOMO→LUMO; 680 nm: 86 %, HOMO→LUMO+1). The two‐photon absorption (TPA) cross section value (σ(2)) of the benzene‐fused porphyrin pentamer was estimated to be 3900 GM at 1500 nm, which is strongly correlated with a cruciform molecular structure with multidirectional π‐conjugation pathways. 相似文献
A novel asymmetric dinuclear gold(I) complex with 3,6-diethynylphenanthroline, 3,6-bis{(PPh3)–Au–C≡C}2-phen, has been synthesized from Au(PPh3)Cl (PPh3 = triphenylphosphine) and 3,6-diethynyl-1,10-phenanthroline. The asymmetrical dinuclear gold(I) complex, 3,6-bis{(PPh3)–Au–C≡C}2-phen, demonstrated a weak phosphorescence assignable to the metal-perturbed 3π–π* transition in the long wavelength region compared to an intense emission of the symmetrical dinuclear complex with 3,8-diethynylphenanthroline,
3,8-bis{(PPh3)–Au–C≡C}2-phen. A similar tendency of phosphorescent bands for the mononuclear gold(I) complexes with 5-ethynylphenanthroline, 5-{(PPh3)–Au–C≡C}-phen, and 3-ethynylphenanthroline, 3-{(PPh3)–Au–C≡C}-phen was observed. The absorption bands assignable to the π–π*(C≡Cphen) transition and phosphorescent emission assignable to the metal-perturbed 3π–π* transition for these four gold(I) complexes were reasonably consistent with the results calculated by DFT and TD-DFT. 相似文献
The combination of vanadium-oxo compounds (3 or 4) with a lipase produced the regio- and enantioconvergent transformation of racemic allyl alcohols (1 or 2) into optically active allyl esters. In this system, the vanadium compounds catalyzed the continuous racemization of the alcohols along with the transposition of the hydroxyl group, while the lipase effected the chemo- and enantioselective esterification to achieve the dynamic kinetic resolution. 相似文献
A new class of 1,3-diphoshacyclobutane-2,4-diyls bearing alkylsulfanyl or arylsulfanyl groups together with the sterically demanding Mes* groups have been prepared as air-stable compounds.
We review some techniques and notions for quantum information theory. It is shown that the dynamical entropies is discussed
and some numerical computations of these entropies are carried for several states. 相似文献
Tetrahydrozerumbone 2, which has a powerful balmy fragrance, has a stereogenic carbon at C2 and can be easily prepared from zerumbone 1, which is one of the most important materials that displays an NMRDOS character. Reduction of 2 gave two diastereomers 3 and 4; their optically active (>99% ee) alcohols were obtained by lipase-catalyzed stereoselective transesterification of each racemic alcohol. The enantioselectivity of tetrahydrozerumbol does not entirely depend on the hydroxyl position but on the 2-methyl position. Compounds (R)-2 and (S)-2 were obtained by Dess–Martin oxidation of the corresponding alcohols. Interestingly, (R)-2 showed a strong balmy fragrance while (S)-2 had hardly any fragrance. 相似文献