A series of donor-acceptor-donor triads 16 consisting of tetrathiafulvalene and naphthalene diimide units were synthesized and characterized. UV/Vis spectroscopic and cyclic voltammetric studies indicate that these triads show negligible intramolecular charge transfer interaction in the ground state. In contrast to that of the reference compound 36, their fluorescence intensities were reduced in the following sequences: 3≈4≈5≈6<1≈2, which is probably due to photoinduced electron transfer in triads 16. Two solid forms (yellow and green) of triads 15 were obtained, while only green form for triad 6 was obtained under the same conditions. Studies of the yellow and green forms with UV, XRD and DSC were performed. It was suggested that varying the attached side groups may regulate intermolecular charge transfer interactions in the solid state.
The reaction of N-n-Bu4MnO4 with Mn(Oac) 2 · 4H2O and butenoic acid in nonaqueous solvents leads to the formation of the complex [Mn3O(O2CCH = CHCH3) 6(py) 3] ClO4 · py (1). The crystal structure was determined.The complex crystallizes in hexagonal, space group P63/m, unit cell parameters, a = 1. 2456(1)nm, b = 1. 2456(1) nm, c = 1. 8741(1) nm, V=2. 5181(3) nm3, Z =2, and final R1 =0. 0565, wR2 =0. 1465. Variable tem-perature solid tate magnetic susceptibility study shows that the complex [Mn3O(O2CCH = CHCH3)6(py)3] ClO4 (2) has an antiferromagnetic exchange interaction.
A series of light-emitting conjugated polymers alternatively involving carbazole and bivinylene arylene moieties in the main chain were synthesized via Wit-tig-Horner type copolymerization. The photoinduced charge transfer process relating to these polymers was investigated by using the technique of fluorescence spectroscopy. The interaction between excited copolymers and C60 in benzene solution was studied. The fluorescence quenching can be well described by the 搒phere-of-action?mechanism. It is be-lieved that two basic steps are involved in the quenching process, i.e. the diffusion of excitation within the conjugated polymers and the dissociation of the exctions trapped by fullerene. The radius of the sphere-of-action can be related to the excitation diffusion length, which depends on the lifetime of the exciton. The dynamic fluorescence quenching of the copolymers by another quencher, 1,4-dicyanobenzene (DCB) was also surveyed. Copolymers with different chain confor-mations show different temperature effects in the dynamic quenching. A planar conformation is beneficial for the quenching via bimolecular collision.
LIN Hongzhen, ZHENG Min, YANG Junlin & BAI Fenglian Laboratory of Organic Solids, Center for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China
