A realistic dynamics simulation study is reported for the photoisomerization of trans-azobenzene. The isomerization follows both n pi* (the HOMO --> LUMO) and pi pi* (the HOMO-1 --> LUMO) excitations. The simulation finds that for the pi pi* excitation, the relaxation of the S(pi pi*) state is immediately followed by double excitation, (pi)(2)(pi*)(2). The decay from the S((pi)(2)(pi*)(2)) state to the S(0) state can occur at partially twisted structure, which favors the formation of the trans isomer. Multiple decay channels are found at about twisted structure for both n pi* and pi pi* excitations. Decay at about twisted geometry leads to the formation of either cis or trans isomer. Opening of the decay channel at partially twisted structure accounts for the smaller isomerization yield for the pi pi* excitation.

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A family of self-assembly lanthanide−organic coordination polymers with both rigid and flexible ligands formulated as {[Ln2(Hpimda)2(μ4-C2O4)·2H2O]·4H2O} n (Ln = Sm (1), Eu (2), Tb (3), Dy (4), Ho (5), Er (6), H3pimda = 2-propyl-1H-imidazole-4,5-dicarboxylic acid) has been synthesized from the reactions of H3pimda with trivalent lanthanide salts in the presence of oxalate as coligand. X-ray diffraction analysis reveals that these complexes are isomorphous and isostructural, and each forms a novel three-dimensional (3D) frameworks structure, in which the metalloligands' two-dimensional (2D) networks were constructed from the lanthanide ion, 2-propyl-imidazole-dicarboxylate as well as oxalate ligands, and the oxalate further acts as a pillar to link the [Ln(Pimda)(oxo)] 2D grids to generate the 3D open frameworks, leaving one-dimensional channels, which are occupied by water clusters displaying an intricate array. The luminescence emission spectra of the complexes vary depending on which lanthanide ion is present. In addition, compounds 3, 4, and 5 exhibited weak but significant ferromagnetic couplings within the two adjacent magnetic centers bridged through oxalato, whereas dominant antiferromagnetic interaction was observed in the erbium compound of 6, respectively.

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The reaction of [Cp 2 Ti(CCPh) 2 ], [Cp 2 Zr(CCPh) 2 ], or [(C 5 H 4 Si-Me 3 ) 2 Zr(CCPh) 2 ] with vanadocene in toluene at room temperature gives [Cp 2 V(m-h 2 :h 4 -butadiyne)MCp ' 2 ] 1 (M Ti, Cp' C 5 H 5 ), 2 (M Zr, Cp' C 5 H 5 ), or 3 (M Zr, Cp' C 5 H 4 SiMe 3 ), respectively. These compounds, which have been characterized by elemental analysis, mass spectrometry, IR and Raman spectroscopy, exhibit similar magnetic susceptibilities. According to an X-ray diffraction analysis of 3, the [Cp 2 V] and Cp ' 2 Zr metallocene moieties are bonded to a butadiene (or butadiyne) framework through the two internal carbon atoms for [Cp 2 V], and though the two internal and the two external carbon atoms for [Cp '2 Zr]. The two internal carbon atoms of the butadiene skeleton are planar and tetracoordinated. 1101 s(alkynyl)metallocene, [Cp ' 2 M(C CPh) 2 ], and vanadocene. These compounds have been characterized by mass spectrometry, magnetic susceptiblity measurements, and IR and Raman spectroscopy. The structural arrangement in compounds has been confirmed by an X-ray crystal structure determination of compound 3.

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