γ-graphyne: A promising electron acceptor for organic photovoltaics

The search for new materials is constantly ongoing. Recently, a two-dimensional carbon allotrope , γ-graphyne, has been synthesized with a unified crystalline structure . Because of its low LUMO and excellent electron mobility, it appears to be a promising electron acceptor for photovoltaic applications. Here we report an analysis of the electronic properties of model van der Waals complexes of γ-graphyne with several partners of different electronic nature. We show that photoinduced electron transfer from electron-donating partners to γ-graphyne is favorable and occurs on nano to picosecond time scale. In contrast, electron transfer from γ-graphyne to strong electron acceptors is unlikely. Our results open perspectives for the future application of γ-graphyne in photovoltaic devices

A simple model for calculating atomic charges in molecules

We propose a new atomic-charge analysis, termed adjusted charge partitioning (ACP) scheme. To partition the molecular electronic density into atomic components, weighting factors cAr2n-2exp(-αAr) with atomic parameters cA and αA are used. Extensive numerical tests were performed for 540 molecules containing 17 main-group elements H, Li to F, Na to Cl, Br, and I. The estimated dipole moments and atomic charges are compared with the data provided by a large number of alternative atomic-charge schemes including the Mulliken, Löwdin, Hirshfeld, Hirshfeld Iterative, CM5, ESP, NPA, and QTAIM population analyses. These tests show that the resulting atomic charges are insensitive to basis sets used, chemically consistent and accurately reproduce experimental dipole moments. © 2018 the Owner Societies

A simple model for calculating atomic charges in molecules

We propose a new atomic-charge analysis, termed adjusted charge partitioning (ACP) scheme. To partition the molecular electronic density into atomic components, weighting factors cAr2n-2exp(-αAr) with atomic parameters cA and αA are used. Extensive numerical tests were performed for 540 molecules containing 17 main-group elements H, Li to F, Na to Cl, Br, and I. The estimated dipole moments and atomic charges are compared with the data provided by a large number of alternative atomic-charge schemes including the Mulliken, Löwdin, Hirshfeld, Hirshfeld Iterative, CM5, ESP, NPA, and QTAIM population analyses. These tests show that the resulting atomic charges are insensitive to basis sets used, chemically consistent and accurately reproduce experimental dipole moments. © 2018 the Owner Societies

Synthesis and optical properties of new 5′-aryl-substituted 2,5-bis(3-decyl-2,2′-bithiophen-5-yl)-1,3,4-oxadiazoles

New photoluminescent donor-acceptor-donor (DAD) molecules, namely 5′-aryl-substituted 2,5-bis(3-decyl-2,2′-bithiophen-5-yl)-1,3,4-oxadiazoles were prepared by palladium-catalyzed coupling from readily available compounds such as ethyl 3-decyl-2,2′-bithiophene-5-carboxylate and aryl halides. The obtained compounds feature increasing bathochromic shifts in their emission spectra with increasing aryl-substituent size yielding blue to bluish-green emissions. At the same time, their absorption spectra are almost independent from the identity of the terminal substituent with λmax values ranging from 395 to 405 nm. The observed trends are perfectly predicted by quantum chemical DFT/TDDFT calculations carried out for these new molecules. © 2017 Kostyuchenko et al.; licensee Beilstein-Institut

Synthesis and optical properties of new 5′-aryl-substituted 2,5-bis(3-decyl-2,2′-bithiophen-5-yl)-1,3,4-oxadiazoles

New photoluminescent donor-acceptor-donor (DAD) molecules, namely 5′-aryl-substituted 2,5-bis(3-decyl-2,2′-bithiophen-5-yl)-1,3,4-oxadiazoles were prepared by palladium-catalyzed coupling from readily available compounds such as ethyl 3-decyl-2,2′-bithiophene-5-carboxylate and aryl halides. The obtained compounds feature increasing bathochromic shifts in their emission spectra with increasing aryl-substituent size yielding blue to bluish-green emissions. At the same time, their absorption spectra are almost independent from the identity of the terminal substituent with λmax values ranging from 395 to 405 nm. The observed trends are perfectly predicted by quantum chemical DFT/TDDFT calculations carried out for these new molecules. © 2017 Kostyuchenko et al.; licensee Beilstein-Institut