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ZINDO
About: ZINDO is a research topic. Over the lifetime, 652 publications have been published within this topic receiving 15949 citations.
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TL;DR: A systematic characterization of methylene-bridged fluorene oligomers constructed of two, four, six, and eight aromatic rings using time-dependent density functional theory, the ab initio approximate coupled-cluster singles and doubles method, and semiempirical spectroscopic Zerner's intermediate neglect of differential overlap method is reported.
Abstract: We report a systematic characterization of methylene-bridged fluorene oligomers constructed of two, four, six, and eight aromatic rings using time-dependent density functional theory (TDDFT), the ab initio approximate coupled-cluster singles and doubles (CC2) method, and semiempirical spectroscopic Zerner's intermediate neglect of differential overlap method (ZINDO/S). Geometry optimizations have been performed for the ground state and for the first electronically excited state. Vertical excitations and the fluorescence transition from the lowest excited state have been calculated. Computed ground-state geometries and infrared spectra for fluorene are in good agreement with experimental results. The RI-CC2 and ZINDO/S absorption and fluorescence spectra agree very well with the available experimental data for studied fluorene oligomers and for para oligophenylenes films. On the other hand, TDDFT calculations underestimate excitation and fluorescence energies systematically for larger systems (N > 4) in comparison with the above-mentioned results. The effective conjugation length was estimated to 13-14 repeat units. The computed radiative lifetimes for the fluorene molecule show good agreement with experiment within realistic expectations. The decrease of the radiatiave fluorescence lifetime with the increase in the conjugation length has been discussed also.
120 citations
TL;DR: In this paper, a donor-acceptor organometallic chromophore bearing the prototypical acceptor −NO2 has been crystallographically studied, and the results are consistent with a substantial increase in quadratic nonlinearity for (i) chain lengthening of the organometallicity of the chromophores, and (ii) an azo linkage compared with an ene linkage.
118 citations
TL;DR: Qualitative ZINDO/SCI quantum chemical calculations indicate that, in [Ni(L)(MePhCHNH2)], the beta orientation strongly depends on the laser wavelength, raising the possibility for a new type of molecular switch.
Abstract: An H2L Schiff-base ligand that was obtained from the monocondensation of diaminomaleonitrile and 4-(diethylamino)salicylaldehyde is reported together with four related nickel(II) complexes formulated as [Ni(L)(L‘)] (L‘ = MePhCHNH2, iPrNH2, Py, and PPh3). Crystal structures have been solved for H2L, [Ni(L)(MePhCHNH2)], and [Ni(L)(iPrNH2)]. Surprisingly, the complexation process leads to the formation of a rather unusual nickel amido (−NH−NiII) bond by deprotonation of the primary amine of H2L. A reduction of the quadratic hyperpolarizability (β) from 38 × 10-30 to 17.5 × 10-30 cm5 esu-1 is evidenced on H2L upon metal complexation by the electric-field-induced second-harmonic (EFISH) technique. Qualitative ZINDO/SCI quantum chemical calculations indicate that, in [Ni(L)(MePhCHNH2)], the β orientation strongly depends on the laser wavelength. In particular, a β rotation strictly equal to 90° could be obtained with 1.022 μm incident light on passing from [Ni(L)(MePhCHNH2] to a hypothetical [Ni(HL)(MePhCHNH2]+...
113 citations
TL;DR: In this paper, a series of organic compounds with first-row elements was calculated to determine the performance of TD-DFRT (time-dependent density functional response theory) and to compare with other approximate or semi-empirical methods.
Abstract: A series of organic compounds with first-row elements was calculated to determine the performance of TD-DFRT (time-dependent density functional response theory) and to compare with the performance of approximate or semiempirical methods (TD-DFRT-TB, ZINDO/S, PM3/S). The mean absolute deviation between theoretical and experimental excitation energies is lowest for TD-DFRT. Because of poor results in some cases the error of TD-DFT was distinctly larger in the calculations of sulfur-free than in the calculation of sulfur-containing compounds. General spectral absorption features are reasonably well reproduced by the approximate TD-DFRT in tight-binding approximation (TD-DFRT-TB) and by semiempirical MO-CI methods based on the NDO (ZINDO/S) or the NDDO approach (PM3/S). If the limitations of ZINDO/S are considered the method is useful in calculating n→π∗- and π→π∗-type transitions.
109 citations
TL;DR: In this paper, a computational model (ZINDO and molecular mechanics) based on the current mechanistic understanding of the reaction is presented, which correctly predicts the dominant diastereomer from the cyclization of α-diazo esters.
Abstract: Rhodium-mediated cyclization of the α-diazo ester 1 proceeds with high diastereoselectivity, to give the trisubstituted cyclopentane 5 A computational model (ZINDO and Molecular Mechanics) based on our current mechanistic understanding of the reaction is presented This model correctly predicts the dominant diastereomer from the cyclization of 1 and the eight (Table 2) other α-diazo esters studied thus far
107 citations