A detailed understanding of the electronic structure of π-conjugated materials can be reached by means of two widely available semiempirical quantum-chemical methods: Austin model 1 (AM1) and intermediate neglect of differential overlap (INDO). This is illustrated by calculating the ultraviolet photoelectron spectra (UPS) of π-conjugated oligomers and polymers and comparing the theoretical data to experimental spectra. The approach is applied here to a series of compounds with varying molecular topology and chemical constitution: oligomers of p-phenylenevinylene and various derivatives, fluorinated derivatives of polyisothianaphthene, and 4,4′-bis(m-tolyphenylamino)biphenyl (TPD). The AM1-and INDOcalculated UPS spectra are also compared to data obtained with the valence effective Hamiltonian method, which is known to provide reliable results for the simulation of UPS spectra of these types of molecules. An easily applicable procedure is proposed to obtain the best fit to the experimental spectra from the AM1 and INDO molecular orbital energies. Both techniques accurately reproduce the lower energy part of the spectrum, which contains the most important part of the π electronic structure; INDO is also found to perform well for the inner part of the UPS spectrum, which mainly corresponds to the σ electronic states.
Three new copolymers with well-defined alternating substituted p-phenylenevinylene (PV) and ethylene oxide (EO) blocks were studied. The multiblock copolymers were synthesized using the Wittig reaction and characterized with GPC, IR, elemental analysis, and 13C and NMR. Thermal properties were studied with DSC and the results compared with those of blends of a model compound and polyethylene oxide). The copolymers are intrinsically soluble and fusible, and free-standing films can be cast from chloroform solutions. Iodine doping of the films from vapor or in solution yields materials with electrical conductivities in the range of 10-3 S cm-1.
Neutron intensities (sin0/A < 0.5/~-1) of zinc bis(hydrogen maleate) tetrahydrate, * Deceased on 23 January 1991. t Author to whom correspondence should be addressed. Zn(C4H304)2.4H2 O, and X-ray intensities (sinO/a ___ 1.1 A -1) of nickel bis(hydrogen maleate) tetrahydrate, Ni(C4HaOa)2.4H20, were collected at room temperature (298 K). Zn salt: M, = 367.5, triclinic, ei, a = 7.337 (5), b = 9.219 (7), c = 5.222 (3) A, a = 0108-2701/92/071192-06506.00
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