Journal of Physical Organic Chemistry最新文献

The potential energy surface (PES) for the reaction of ozone with dimethyl sulfide (DMS) was calculated at the CCSD(T)/6-311++G(3df,2pd)//M06-2X/6-311++G(d,p) levels of theory. Result shows that on the singlet PES the addition–elimination mechanism is dominant, and H-abstraction mechanism is less competitive. The major channel starts from the addition of ozone and DMS leading to a weak intermediate IM1, which decomposes subsequently to DMSO and ¹O₂ via a barrier around 38.8 kJ/mol. With a barrier of 64.0 kJ/mol, the formation of HO₃ + CH₃SCH₂ via H-abstraction mechanism is subdominant. Besides, DMSO + ¹O₂ can take place further reactions to produce several products. The substitution mechanism was located on the triplet PES, however, with a rather high barrier it is negligible. Furthermore, the rate constants for the two channels leading to DMSO + ¹O₂ and HO₃ + CH₃SCH₂ were calculated from 200 to 1000 K. The total rate constant is 1.13 × 10^-20 cm³·molecule^-1·s^-1 at 298 K and 1 atm, in good agreement with previous experimental data. The overall rate constants are positive temperature dependent in the whole temperature range.

Organic solar cells (OSCs) have grabbed the attention of researchers due to good power conversion efficiency, low cost, and ability to compensate for light deficit. The aim of the present research work is to increase the efficiency of previously synthesized reference (R) molecule 2,2′-((2Z,2′Z)-(((4,4′-dimethyl-[2,2′-bithiazole]-5,5′-diyl)bis(4-(2-butyloctyl)thiophene-5,2-diyl))bis (methaneylylidene))bis(5,6-dichloro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile by improving its photovoltaic properties via end cap engineering. Five new acceptors, namely, E1, E2, E3, E4, and E5, are used to substitute the end group of reference molecule. Several parameters have been analyzed using density functional theory including the absorption maxima, charge transfer analysis, frontier molecular orbital (FMO), open circuit voltage (V_oc), density of states (DOS), photochemical characteristics, transition density matrix (TDM), and the electron-hole reorganization energies to evaluate the efficiency of specially engineered molecules. All the engineered molecules (D1-D5) had smaller energy gap (4.50–4.71 eV) compared with reference (4.75 eV) and absorption maxima in the range of 443.37–482.67 nm in solvent phase due to end-cap acceptor modification. Fabricated molecules (D1-D5) showed smaller electron reorganizational energy values (0.18–0.27 eV) and V_oc ranging from 1.94 to 2.40 eV. Designed molecule D3 being an acceptor when blended with donor polymer (PTB7-Th) portrayed highest charge transfer capability owing to its smallest energy gap (4.50 eV) among all the engineered molecules. D5 molecule exhibits higher V_oc (2.40 eV), greater LHE (0.9988), and superior result of fill factor (94.15%) as compared with R, which leads to improve the efficiency of OSCs. Theoretical findings illustrated the superior behavior of all the designed molecules making them suitable aspirants to construct efficient OSC devices.

We have investigated the stereoselectivity and reactivity of the sodium borohydride reduction of 2-X-cyclohexanones (X=H, Cl, Br) using a combined approach of competitive experiments and density functional theory calculations. Our results show that the hydride addition proceeds via a late transition state in which the C–H bond is nearly formed, consistent with the mild reducing power of NaBH₄. The reaction barrier decreases from the 2-halocyclohexanones to the unsubstituted cyclohexanone, in line with relative reactivities observed in the competitive experiments. Furthermore, we provide a protocol to solve the longstanding issue of properly modelling the axial–equatorial facial selectivity of hydride addition to the carbonyl group substituted with a vicinal polar group. The inclusion of implicit solvation in combination with an explicit solvent molecule is crucial to reproduce the stereoselective formation of the cis product observed experimentally.

In this work, the rate-determining steps of the OH radical + 3-bromopropene gas phase reaction were studied, which could explain for the possible negative activation energy observed in experiments. To obtain new kinetic parameters and data for critical revisions, a reinvestigation of the rate coefficient (k) and its temperature dependence was carried out using the PLP-LIF technique, in the 254- to 371-K range. Moreover, quantum-mechanical and canonical variational transition state theory calculations were performed, taking into consideration four OH addition and two β-hydrogen atom abstraction reaction channels. The proposed kinetic model fits to the observed experimental Arrhenius behavior, and three not negligible reaction pathways are described for the first time.

Thiophene and pyridine compounds are widely used in medicine, pesticides, and material fields, and study of their physical and chemical changes under an external electric field (EEF) will improve a deep understanding of their properties. In this work, we selected 3-Chlorothieno[2,3-b]pyridine-2-carbonitrile (CPC) as the representative and explored the structure, total energy, dipole moment, Hirshfeld charge, molecular electrostatic potential, infrared, Raman, and UV-Vis spectra of CPC under EEF through density functional theory (DFT). The calculations indicated that the bond length, the bond angle, total energy, dipole moment, and energy gap of CPC are strongly affected by EEF. Infrared, Raman, and UV-Vis spectra showed stark vibration effects with increasing EFF. Our results provide a basis for further applications of CPC with and without EEF.

Organic molecules have been extensively utilized in various applications including materials science, chemical, and biomedical fields. Traditionally, the design of organic molecules is achieved through experimental approaches, guided by conceptual insights, intuition, and experience. Although these experimental approaches have been successfully utilized to unveil various high-performance materials, these methods show serious limitations due to vast design space and the ever-increasing demand for organic molecules (new materials). Artificial intelligence with computer science is used by modern researchers to design materials with better performance and for predicting the properties of new materials. Herein, benzofuran-based building blocks are used as a standard molecule to search for new building blocks. Similarity analysis is performed to screen/search potential candidates for photodetectors based on the chemical structural similarity. Extended-connectivity fingerprints (ECFPs) are used for the similarity analysis. The virtual libraries of unique monomers are enumerated. The breaking retro-synthetically interesting chemical substructures (BRICS) method is also used to design building blocks by automatically decomposing and combining monomers in enumerated libraries. Moreover, this work offers a potential way to identify new monomers for photodetectors cost-effectively and rapidly.

In this paper, several Ir (III) complexes with transition metal as the central atom formed by the corresponding combination of two main ligands and three auxiliary ligands have been studied theoretically. The electronic structure, frontier molecular orbital, and spin orbit coupling data are used to analyze its application value in light emitting devices. The density functional theory is used to study (tbi)₂Ir(bpp), (tbi-c)₂Ir(bpp), (tbi)₂Ir(dbm), (tbi-c)₂Ir(dbm), (tbi)₂Ir(pic), and (tbi-c)₂Ir(pic). bpp = (2Z)-3-hydroxy-13-diphenylprop-2-en-1-one; dbm = 1,3-di-phenyl-1, 3-propanedione; pic = picolinate.

The careers of two pioneers of modern physical organic chemistry, Sir Christopher K. Ingold and Saul Winstein, are discussed and compared. Despite the fact that Ingold received 112 nominations from 77 nominees for the Nobel Prize in Chemistry (NPch), he never received that award. Winstein, also a non-recipient of the NPch, died prematurely at the age of 57. In his last 3 years, Winstein received 22 nominations from 18 nominators, seven of whom received or would receive the NPch themselves. Analyses of the Nobel Nomination Archive along with other evidence are used to explain Ingold's experience. A detailed examination of Winstein's career along with relevant historical data suggests that Winstein was a highly probable Nobelist had he lived just a few years longer. The relationship of Ingold's and Winstein's careers and the politics of the Nobel Prize selection process including the possibility that they would have shared a Nobel Prize are presented.

Hydrogen atom-donating ability of alkane is a research hotspot and has been extensively studied. In this article, the second-order rate constants of 20 hydrogen atom transfer (HAT) reactions between aliphatic, benzylic, and allylic alkanes and alkane derivatives with CumO^• in acetonitrile at 298 K were studied. The thermo-kinetic parameter ΔG^≠o(XH), bond dissociation free energy ΔG^o(XH), and kinetic intrinsic resistance energy ΔG^≠_XH/X were determined and used to evaluate the H-donating abilities of these substrates in thermodynamics, kinetics, and HAT reactions. Structure–activity relationships including the factors (electronic, stereoelectronic, and steric effects), introduction of CH₃, Ph, or Cl in alkanes, and introduction of N atom in cycloalkane were discussed carefully. The results show that the order of H-donating abilities is allylic alkanes > cycloalkanes > chain alkanes ≈ benzylic alkanes > haloalkanes. The introduction of CH₃, Ph, or Cl in alkanes and the introduction of N atom to the carbon ring reduce ΔG^o(XH) but increase ΔG^≠_XH/X, and ΔG^≠o(XH) is the synthesis result of these two parameters. The reliability of ΔG^≠o(XH) was verified, and the accuracy and reliability of the parameters were proved. Through the study of this paper, not only the ΔG^o(XH), ΔG^≠_XH/X, and ΔG^≠o(XH) of these alkanes and derivatives in HAT reaction can be quantitatively evaluated but also the structure–activity relationship of alkane is clearly researched.