1,720,984 research outputs found
General strategy for computing nonlinear optical properties of large neutral and cationic organic chromophores in solution
No full textTuning of nonlinear optical (NLO) properties of organic chromophores (OCs) by stereo-electronic and environmental effects has been widely documented by different experimental techniques and theoretical studies. Disentanglement and analysis of the different contributions requires, however, the availability of effective yet accurate quantum mechanical approaches for medium to large size systems in their natural environment. As a first step, we have shortly reviewed the phenomenological models still used by experimentalists to interpret their results and shown that a quantum mechanical approach based on the density functional theory (DFT) and the polarizable continuum model (PCM) should be able to overcome most theoretical limitations allowing, at the same time, the study of large systems with reasonable computational resources and the analysis of the results in terms of well-defined physical-chemical effects. After validation of the most suitable density functional/basis set in conjunction with the PCM description of bulk solvent effects, we have performed a systematic study of representative OCs, especially cationic ones, with special reference to their first order hyperpolarizability. The internal consistency of the results and their good agreement with experiment paves the route toward integrated experimental/computational studies of NLO properties taking together physical soundness, feasibility, reliability, and ease of interpretation
Quenching of the Photoisomerization of Azobenzene Self-Assembled Monolayers by the Metal Substrate
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First principle evaluation of the chiroptical activity of the di-phenyl-diazene derivatives
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
An integrated computational tool to model the broadening of absorption bands of flexible dyes in solution: cationic chromophores as test cases
No full textThis paper is devoted to the development and application of an effective computational approach for the prediction of band broadening in the electronic spectra of semi-flexible organic molecules in solution. The protocol is based on DFT, TD-DFT, and PCM computational techniques and attempts to take into account the three main contributions tuning electronic spectra, namely vibronic transitions, conformational equilibria, and solvent relaxation. The whole procedure has been implemented in the Gaussian code and has been tested for the interpretation of the spectroscopic behaviour of a betainic dye and a series of charged dyes, containing one methyl-pyridinium or quinolinium group and a flexible moiety. The results provide a comprehensive picture of solvatochromic effects and offer a reliable answer to the open problem of the origin of band broadening in the target semi-flexible dyes
Preliminary note on the effect of denzimol in partial epilepsy.
No full textThe antiepileptic activity of the imidazole derivative denzimol has been evaluated in 10 patients with poorly controlled partial epilepsy by adding on the drug to the current therapy, in an open preliminary trial. A sustained drop in seizure frequency greater than 50\% occurred in 5 patients. Although denzimol increased blood concentrations of carbamazepine, correlation analysis indicated that the improvement was more likely due to intrinsic properties of denzimol. No severe side effects were reported, although several patients experienced nausea and vomiting, which caused 2 patients to drop out
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