Adsorption of rare bases on transition metal doped γ-graphyne nanosheets: a DFT study.

Detection of rare bases (RBs) is key to understanding biological complexity, rapidly diagnosing genetic diseases and advancing personalized medicine. Electrochemical sensors are one of the most promising methods for RB detection, but their low responsiveness limits their effectiveness. Therefore, enhancing selectivity and sensitivity is necessary.

Screening novel candidates of ZL003-based organic dyes for dye-sensitized solar cells by modifying auxiliary electron acceptors: A theoretical study.

In this work, a series of ZL003-based free-metal sensitizers with the donor-acceptor-π- conjugated spacer-acceptor (D-A-π-A) structure were designed by modifying auxiliary electron acceptors for the potential application in dye-sensitized solar cells. The energy levels of frontier molecular orbitals, absorption spectra, electronic transition, and photovoltaic parameters for all studied dyes were systematically evaluated using density functional theory (DFT)/time-dependent DFT calculations. Results illustrated that thienopyrazine (TPZ), selenadiazolopyridine (SDP), and thiadiazolopyridine (TDP) are excellent electron acceptors, and dye sensitizers functionalized by these acceptors have smaller HOMO-LUMO gaps, obviously red-shifted absorption bands and stronger light harvesting.

studies on graphyne (GY) for the detection of rare bases in DNA.

Graphyne (GY) and functionalized GY have become cutting-edge research materials for the scientific community. In the present work, the adsorption of rare bases -cytosine (Cyt), 5-methylcytosine (5-meCyt), 5-hydroxymethylcytosine (5-hmCyt), 5-formoxylcytosine (5-fCyt), and 5-carboxylcytosine (5-caCyt) on pristine, B- and N-doped γ-GY was investigated by the first-principles density functional method; methods were designed to distinguish these rare bases by the translocation time and sensitivity. Initially, the stability of pristine, B- and N-doped γ-GY was ascertained by the cohesion energy, and the electronic properties were also analyzed by the energy gap and density of state (DOS).

Atmospheric chemistry of the self-reaction of HO radicals: stepwise mechanism versus one-step process in the presence of (HO) (n = 1-3) clusters.

The effects of water on radical-radical reactions are of great importance for the elucidation of the atmospheric oxidation process of free radicals. In the present work, the HO2 + HO2 reactions with (H2O)n (n = 1-3) have been investigated using quantum chemical methods and canonical variational transition state theory with small curvature tunneling. We have explored both one-step and stepwise mechanisms, in particular the stepwise mechanism initiated by ring enlargement.

Correction: Effects of water, ammonia and formic acid on HO + Cl reactions under atmospheric conditions: competition between a stepwise route and one elementary step.

[This corrects the article DOI: 10.1039/C9RA03541A.].

Effects of water, ammonia and formic acid on HO + Cl reactions under atmospheric conditions: competition between a stepwise route and one elementary step.

Quantum chemical calculations at M06-2X and CCSD(T) levels of theory have been performed to investigate the effects of HO, NH, and HCOOH on the HO + Cl → HCl + O reaction. The results show that catalyzed reactions with three catalysts could proceed through two different mechanisms, namely a stepwise route and one elementary step, where the former reaction is more favorable than the latter. Meanwhile, for the stepwise route, a single hydrogen atom transfer pathway in the presence of all catalysts has more advantages than the respective double hydrogen atom transfer pathway.

Catalytic effect of (HO) ( = 1-3) on the HO + NH → NH + O reaction under tropospheric conditions.

The effects of (HO) ( = 1-3) clusters on the HO + NH → NH + O reaction have been investigated by employing high-level quantum chemical calculations with M06-2X and CCSD(T) theoretical methods, and canonical variational transition (CVT) state theory with small curvature tunneling (SCT) correction. The calculated results show that two kinds of reaction, HO⋯(HO) ( = 1-3) + NH and HN⋯(HO) ( = 1-3) + HO, are involved in the (HO) ( = 1-3) catalyzed HO + NH → NH + O reaction. Due to the fact that HO⋯(HO) ( = 1-3) complexes have much larger stabilization energies and much higher concentrations than the corresponding complexes of HN⋯(HO) ( = 1-3), the atmospheric relevance of the former reaction is more obvious with its effective rate constant of about 1-11 orders of magnitude faster than the corresponding latter reaction at 298 K.

Molecular and dissociative O adsorption on the CuO(111) surface.

The adsorption of O2 on the Cu2O(111) surface at different coverages has been studied by spin-polarized density functional theory (DFT+U) calculations and atomic thermodynamics. It has been found that the dissociative O2 prefers to adsorb on the reconstructed Cu2O(111) surface at low coverages (1/4 to 1 monolayer), while totally dissociative and mixed molecular and dissociative O2 prefers to adsorb on the reconstructed Cu2O(111) surface thermodynamically at higher coverages (5/4 to 7/4 monolayers). More interesting is that the CuO film can be automatically formed on the Cu2O(111) surface that was induced by the surface reconstruction of the Cu2O(111) surface and adsorption of four dissociative O2 molecules (1 monolayer), which agrees well with the recent experimental results.

Changing molecular conjugation with a phenazine acceptor for improvement of small molecule-based organic electronic memory performance.

Two conjugated small molecules with different molecular conjugation, 4',4''-(diazene-1,2-diyl)bis(2',3',5',6'-tetrafluoro-,-diphenyl-[1,1'-biphenyl]-4-amine) (TPA-azo-TPA) and 4,4'-(perfluorophenazine-2,7-diyl)bis(,-diphenylaniline) (TPA-ph-TPA), in which the electron donor triphenylamine moiety is bridged using different electron-accepting azobenzene or phenazine blocks, were designed and synthesized. The TPA-ph-TPA molecule with a larger conjugation acceptor regularly formed a nanocrystalline film and the as-fabricated memory devices exhibited outstanding non-volatile write once read many (WORM) memory effects with an ON/OFF ratio ten times higher than that of TPA-azo-TPA. Using theoretical calculations, it was speculated that the memory performance is a result of an electric field induced charge transfer effect and the enhanced device performance of the acceptor molecular conjugation is because of the presence of a strong charge transfer effect.

Correction: Formic acid catalyzed isomerization of protonated cytosine: a lower barrier reaction for tautomer production of potential biological importance.

Correction for 'Formic acid catalyzed isomerization of protonated cytosine: a lower barrier reaction for tautomer production of potential biological importance' by Lingxia Jin et al., Phys. Chem.

Theoretical investigation on exciton-dissociation and charge-recombination processes of PC61BM-PTDPPSe interface.

Designing and synthesizing novel electron-donor polymers with the high photovoltaic performances has remained a major challenge and hot issue in organic electronics. In this work, the exciton-dissociation (k dis ) and charge-recombination (k rec ) rates for the PC61BM-PTDPPSe system as a promising polymer-based solar cell candidate have been theoretically investigated by means of density functional theory (DFT) calculations coupled with the non-adiabatic Marcus charge transfer model. Moreover, a series of regression analysis has been carried out to explore the rational structure-property relationship.

Can a single water molecule really affect the HO2 + NO2 hydrogen abstraction reaction under tropospheric conditions?

The effect of a single water molecule on the HO2 + NO2 hydrogen abstraction reaction has been investigated by employing B3LYP and CCSD(T) theoretical approaches with the aug-cc-pVTZ basis set. The reaction without water has three types of reaction channels on both singlet and triplet potential energy surfaces, depending on how the HO2 radical approaches NO2. These correspond to the formation of trans-HONO + O2, cis-HONO + O2 and HNO2 + O2.

Theoretical investigation on the crystal structures and electron transport properties of several nitrogen-rich pentacene derivatives.

Exploring and synthesizing new simple n-channel organic semiconductor materials with large electron mobility and high air stability have remained a major challenge and hot issue in the field of organic electronics. In the current work, the electron transport properties of four novel nitrogen-rich pentacene derivatives (PBD1, PBD2, PBD3, and PBD4) with two cyano groups as potential n-channel OFET materials have been investigated at the molecular and crystal levels by means of density functional theory (DFT) calculations coupled with the prediction of crystal structures and the incoherent charge-hopping model. Calculations reveal that the studied compounds, which possess low-lying frontier molecular energy levels, large ionization potentials and electron affinities, are very stable exposed to air.