Electronic structure of tetraphenyldithiapyranylidene : A valence effective Hamiltonian theoretical investigation

We present a theoretical investigation of the electronic structure of tetraphenyldithiapyranylidene (DIPSΦ4) using the nonempirical valence effective Hamiltonian (VEH) method. Molecular geometries are optimized at the semiempirical PM3 level which predicts an alternating nonaromatic structure for the dithiapyranylidene (DIPS) framework. The VEH one‐electron energy level distribution calculated for DIPSΦ4 is presented as a theoretical XPS simulation and is analyzed by comparison to the electronic structure of its molecular components DIPS and benzene. The theoretical VEH spectrum is found to be fully consistent with the experimental solid‐state x‐ray photoelectron spectroscopy (XPS) spectrum and an excellent quantitative agreement between theory and experiment is achieved when comparing the energies of the main peaks. A detailed interpretation of all the experimental photoemission bands is reported in the light of the VEH [email protected] ; [email protected]

Planarity vs. Non-Planarity in the Electronic Communication of TCAQ-Based Push-Pull Chromophores

Donor-acceptor alkynes, endowed with 11,11,12,12-tetracyano-9,10-anthraquinodimethane (TCAQ) and N,N-dimethylaniline (DMA) units, have been further functionalized by a [2+2] tetracyanoethylene (TCNE) cycloaddition followed by a subsequent retroelectrocyclization to form distorted non-planar molecular structures with 1,1,4,4-tetracyanobuta-1,3-diene (TCBD) bridge ligands. Comprehensive spectroscopic, electrochemical, and computational studies have been carried out to compare the electronic communication in these planar (alkyne) and nonplanar (with TCBD units) TCAQ-based push-pull chromophores. Cyclic voltammetry and UV-Vis absorption measurements confirm a noticeable electronic communication between the TCAQ and DMA units regardless the quasi-orthogonal arrangement of the two dicyanovinyl halves of the TCBD groups, which partially hinder the electronic communication. The experimental trends are strongly supported by theoretical calculations performed at the density functional theory level, which further evidence an active electron-withdrawing role of the TCBD bridge both in the formation of the charged species and in the lowest-lying absorption features. The novel push-pull TCAQ-based derivatives including the TCBD bridge show a broad absorption in the whole visible range while having a structure highly distorted from planarity. These chromophores may therefore be viewed as appealing candidates to be exploited in photovoltaic devices with minimal aggregation phenomena

Weighting non-covalent forces in the molecular recognition of C60. Relevance of concave–convex complementarity

The relative contributions of several weak intermolecular forces to the overall stability of the complexes formed between structurally related receptors and [60]fullerene are compared, revealing a discernible contribution from concave–convex complementarity.Viruela Martin, Pedro Manuel, [email protected] ; Viruela Martin, Rafael, [email protected] ; Orti Guillen, Enrique, [email protected]

Efficient light harvesters based on the 10-(1,3-dithiol-2-ylidene) anthracene core

4 pags, 4 figs, 1 tab. -- Supporting Information is available at the Publisher's webThree new push-pull chromophores based on the 10-(1,3-dithiol-2-ylidene) anthracene core were synthesized and fully characterized. The new chromophores display broad absorption spectra, nearly covering the whole visible region, with high extinction coefficients. Electrochemistry and theoretical calculations allowed the understanding of these singular electronic properties. The molecular structures were unambiguously confirmed by X-ray diffraction. © 2013 American Chemical Society.This work has been supported by the MINECO of Spain (CTQ 2011-27934, CTQ2011-24652, CTQ2012-31914, and Consolider-Ingenio CSD 2007-00010 on Molecular Nanoscience), the Comunidad de Madrid (MADRISOLAR-2, S2009/PPQ-1533), the Generalitat Valenciana (Prometeo/2012/053), and the EU project (FUNMOLS FP7-212942-1). J.L.D. thanks the MINECO for a Ramón y Cajal Fellowship. P.-A.B. thanks IMDEA-Nanociencia for a postdoctoral research grant. J.C. acknowledges MECD (Spanish Ministry of Education, Culture, and Sport) for a FPU grant. L.I. thanks Comunidad de Madrid (Spain) for support (BIPEDD-2: S2010-BMD-2457)

Efficient Light Harvesters Based on the 10-(1,3-Dithiol-2-ylidene)anthracene Core

International audienceSolar energy represents nowadays one of the most realistic alternatives to the use of fossil fuels. Photovoltaic devices based on organic compounds (OPV) have experienced a tremendous development in the last years, 1 and recently efficiencies around 8-10% have been 1 (a) Thompson, B. C.; Frechet, J. M. J. Angew. Chem., Int. Ed. 2008, 47, 58-77. (b) Delgado, J. L.; Bouit, P.-A.; Filippone, S.; Herranz, M. A.; Martín, N. Chem. Commun. 2010, 46, 4853-4865. (c) Li, C.-Z.; Yip, H.-L.; Jen, A. K.-Y, J. Mater. Chem. 2012, 22, 4161-4177. (d) Lin ,Y.; Li, Y.; Zhan, X.; Chem. Soc. Rev. 2012, 41, 4245-4272. reported. 2 One of the crucial points to understand this improvement is the careful election of suitable organic materials able to fulfill some energetic and electronic requirements. Among these requisites, the ability of the material to harvest sunlight in a broad range of the visible and NIR spectrum is decisive in order to obtain a suitable photoresponse. In this regard, organic chromophores such as push-pull systems, displaying outstanding absorption 2 (a) Huo, L.; Zhang, S.; Guo, X.; Xu, F.; Li, Y.; Hou, J. Angew. Three new push-pull chromophores based on the 10-(1,3-dithiol-2-ylidene)anthracene core were synthesized and fully characterized. The new chromophores display broad absorption spectra, nearly covering the whole visible region, with high extinction coefficients. Electrochemistry and theoretical calculations allowed the understanding of these singular electronic properties. The molecular structures were unambiguously confirmed by X-ray diffraction. Slow eva

Donor-π-Acceptors Containing the 10-(1,3-Dithiol-2-ylidene)anthracene Unit for Dye-Sensitized Solar Cells

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