In this article, electrical conductivity of aluminum chloride (AlCl₃) and 1-butyl-3-methylimidazolium chloride (BMIC) ionic liquid electrolytes was reported as a function of temperature and AlCl₃ mole fraction. Electrical conductivity increases when the mole fraction of AlCl₃ is between 0 and 0.50 and decreases when the concentration of AlCl₃ exceeds 0.50. An anionic species distribution profile was developed to correlate electrical conductivity, and it was found that AlCl4− anion mainly influences the electrical conductivity of AlCl₃:BMIC electrolytes.

Abstract

Electrical conductivity (σ) of aluminum chloride (AlCl₃) and 1-butyl-3-methylimidazolium chloride (BMIC) ionic liquid (IL) was investigated as a function of temperature and AlCl₃ mole fraction ( XAlCl3). Electrochemical impedance spectroscopy was used to measure the electrical conductivity. Composition of AlCl₃:BMIC ionic liquid was varied by changing the XAlCl3 from 0 to 0.67. The temperature was changed from 70°C to 110°C at 10°C intervals. It was found that the electrical conductivity increases with an increase in temperature. Electrical conductivity increases with XAlCl3 from 0 to 0.5 and then starts to decrease after XAlCl3 = 0.5. A species concentration profile was developed based on thermodynamic model at room temperature for the IL containing BMI+, Cl−, AlCl4−, Al2Cl7−, Al3Cl10−, Al4Cl13−, and Al2Cl6 at different XAlCl3. The only anion species presents between 0 and 0.5 XAlCl3 are Cl− and AlCl4−. Anions like Al2Cl7−, Al3Cl10−, Al4Cl13−, and Al2Cl6 are found at higher XAlCl3. A good agreement between the model and the experimental data was obtained. The variations in anion concentration, molecular structure, and cation–anion interactions are to be the causes of the changes in electrical conductivity of AlCl₃:BMIC system.

No abstract is available for this article.

The careers of two pioneers of modern physical organic chemistry, Sir Christopher K. Ingold (photograph on the left) and Saul Winstein, are reviewed. That neither of these eminent scholars received the Nobel Prize in Chemistry is discussed in light of their numerous and timely nominations for this award. Nomination data comes from the Nobel Foundation's Nomination Archive.

Abstract

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.

The structure, total energy, dipole moment, Hirshfeld charge, molecular electrostatic potential, infrared, Raman, and UV-Vis spectra of 3-chlorothieno[2,3-b]pyridine-2-carbonitrile (CPC) under EEF through density functional theory. 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 effect with the increasing EFF. Our results provide a basis for further applications of CPC with and without EEF.

Abstract

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.

Structure–activity relationship of alkanes and derivatives for the abilities of C(sp³)H bonds toward their H-atom transfer reactions is researched by bond dissociation free energy ΔG ^o(XH), intrinsic resistance energy ΔG ^≠ _XH/X, and thermo-kinetic parameter ΔG ^≠o(XH).

Abstract

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.

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 used to design building blocks by automatically decomposing and combining monomers in enumerated libraries.

Abstract

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.

Experimental and theoretical studies on the OH + CH₂ = CHCH₂Br reaction have been performed. New pathways have been proposed in the mechanisms. Canonical variational transition state theory had a good performance predicting experimental results.

Abstract

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.

2-Halocyclohexanones are more reactive than cyclohexanone itself, and the main product is cis. However, only microsolvation could properly model the reduction reaction pathway involving the polar transition states.

Abstract

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.

Photo-induced excitation enhances intramolecular hydrogen bonding interactions for CHPHI compound. Enhanced hydrogen bond OH⋯N facilitates ESIPT tendency. ICT further promotes the occurrence of ESIPT reaction for CHPHI system. Nonpolar solvent environment is more favorable for ESIPT behavior of CHPHI fluorophore.

Abstract

Excited-state intramolecular proton transfer (ESIPT) reaction, as one of the most fundamental photochemical behaviors, plays a crucial role in the design of novel optical materials. This study investigates the photo-induced hydrogen bonding behaviors and related ESIPT process of 3-(1H-phenanthro[9,10-d]imidazol-2-yl)-9-phenyl-9H-carbazol-4-ol (CHPHI) in solvents with varying polarities. Based on analyses of the core-valence bifurcation (CVB) index, geometrical structure parameters, topological analysis, and infrared (IR) vibrational spectra, we infer that light excitation facilitates the enhancement of intramolecular hydrogen bonding. This phenomenon can promote the ESIPT process. In particular, we have observed that the enhancement of hydrogen bonding becomes more pronounced as solvent polarity weakens. To further investigate the relationship between solvent polarity and ESIPT behavior, we conduct an exploration of the frontier molecular orbitals (MOs) in CHPHI. Finally, by comparing the magnitudes of excited-state barriers in different solvents, we claim that nonpolar solvents drive the ESIPT reaction for CHPHI fluorophore.

A select history of dichlorocarbene chemistry between 1950 and 2010 will be presented. This is not a comprehensive review; rather, it is a personal perspective on the contributions of two respected colleagues. Jack Hine discovered a new mechanism—alpha elimination—to form carbenes. Moss (and his preceptor Closs) discovered the concept of carbenoids. Dichlorocarbene is the reactive intermediate that spanned the research efforts of Hine and Moss and stimulated their important contributions to organic synthesis and mechanistic thinking.

Abstract

A select history of dichlorocarbene chemistry between 1950 and 2010 will be presented. This is not a comprehensive review; rather, it is a personal perspective on the contributions of two respected colleagues, the reactive intermediate that spanned their research efforts, and their important contributions to organic synthesis and mechanistic thinking.