Journal of Physical Organic Chemistry最新文献

Herein, a series of fluorinated quinoxaline core–based chromophores (MTH1-MTH6) with A₁–π–A₂–π–A₁ configuration was designed by structural modulation of end-capped acceptors in MTHR. The quantum chemical calculations were accomplished at MPW1PW91/6-311G(d,p) functional to explore optoelectronic and photovoltaic properties of these designed compounds. The findings revealed that all the derivatives exhibited narrow band gap (E_gap = 2.163–2.666 eV) with red shift spectra (610.24–766.944 eV in chloroform) as compared with MTHR. The designed compounds exhibited comparable open-circuit voltage (V_oc) and higher power conversion efficiencies (PCEs) as compared with the MTHR. Among the entitled chromophores, MTH1 was found to be a promising chromophore for organic solar cells (OSCs) owning to its lowest E_gap (2.163 eV) with highest absorption peak (766.944 nm in chloroform and 717.709 nm in gaseous phase). The aforementioned findings indicate that molecular engineering of chromophores with extended acceptors enhances photovoltaic response, and this motivates researchers to develop highly effective photovoltaic devices.

The design and synthesis of insensitive energetic materials are a necessary and challenging work. The synthesis of novel nitrogen-rich salts based on 5-(5-Nitro-1H-1,2,4-triazol-3-yl)-1H-tetrazole (H₂NTT) has been presented. Structural characterization of these two salts was accomplished by utilizing NMR, MS, IR spectroscopy, and X-ray diffraction. The standard heats of formation were calculated, and the differential scanning calorimetry (DSC) and sensitivity test were carried out. Their detonation performances were estimated by EXPLO 5 program. These newly synthesized salts showed highly positive heat of formation and low sensitivity. It is noteworthy that the diaminoguanidine salt b exhibited good detonation performance superior to traditional explosive TNT (Trinitrotoluene), making it a prospective candidate for insensitive energetic material.

Ratiometric optical detection of analytes is a convenient strategy as the technique is devoid of relative error and background correction. Herein, solvent-guided ratiometric optical recognition of fluoride and bisulfate anions by a low-cost, “off-the-shelf” bioactive molecule, harmane (HRH) is thoroughly explored. Interestingly, solvent plays a dynamic role in the selective recognition of the dual anions via the dual channels of HRH in an intelligent manner. The probe displays high-fidelity recognition behavior towards fluoride ion in an aprotic solvent (acetonitrile) and towards bisulfate ion in a protic environment (acetonitrile/water; 5:1; v/v). Both the channels of HRH are very selective for a particular anion (F⁻/HSO₄⁻) in a specific solvent. Organized and comprehensive theoretical calculation denotes that hydrogen bonding between the acidic pyrrolic proton of HRH and fluoride for the first channel and the acidic proton of bisulfate and the pyridinic nitrogen for the second channel of HRH led to the formation of a hydrogen-bonded ion pair (HBIP). Consequently, significant optical changes are observed in the visible region, which is convenient for real-life detection of F⁻ and HSO₄⁻ independently. The essential role of solvent in tuning the dual channels of HRH is an important artifact in the literature of fundamental photochemistry.

Development of new high-energy materials (HEMs) is one of the thrust areas of research. These compounds are important for various applications such as propellants, gas generations, explosives in mining, construction, civil and military applications, and safety equipment for national security and defense. HEMs based on imidazole frameworks are currently getting research spotlight due to their exceptional detonation performance with optimum sensitivity. This study reports five imidazole derivatives containing azido/nitro/nitrato/fluoro functional groups. These groups are viable options to design promising explosives with moderate sensitivity. Density functional theory (DFT) method is adopted to determine the geometries, thermodynamic properties, detonation properties, and impact sensitivity of the designed molecules. All the compounds have high density in the range of 1.89–2.03 g/cm³ along with high heat of formation. These compounds aid in new strategy to design HEMs with optimum sensitivity.

The title compound, C₁₇H₂₅N₃O₃S₂, hereafter 1, has been prepared and fully characterized by FTIR, ¹H NMR and ¹³C NMR. Its crystal structure was determined by single-crystal X-ray diffraction. The crystal packing is stabilized by weak CH···O and CH···π interactions. The CLP-Pixel method was used to quantify the energetically significant molecular dimers. The intermolecular contacts were identified and quantified using Hirshfeld surfaces (HS) and the corresponding fingerprint plots. The main contributions to the HS of 1 come from HH, OH/HO and CH/HC contacts, which cover about 93% of the total HS surface. The enrichment ratios showed that the favorable contacts accountable for the crystal packing are consistent with their contributions to the HS. Interaction region indicator (IRI) analysis was used to visualize the location and type of intermolecular contacts, allowing identify the CH···O contacts as van der Waals interactions. To visualize the 3D topology of interactions in the crystal structure, interaction energy values were used to construct energy framework diagrams, which showed that the dispersion energy dominates over other interaction energies, as expected for crystal packing governed by weak interactions. Finally, a combination of MEP surface, QTAIM and NCIplot analysis energetically confirmed the existence of CH···O and O···O dichalcogen interactions.

The present work explored the effect of –OH group substitution (o/p) on the spectral and electrochemical behavior of N-benzylideneaniline. The geometry optimization of unsubstituted and (o/p)-OH-substituted analogs revealed the coplanarity of the molecules. The vibrational spectra of the compounds were computed using density functional theory (DFT) and compared with the experimental data. The observed bands were assigned based on total energy distribution (TED). Predicted electronic absorption spectra from time-dependent density functional theory (TD-DFT) calculation were compared with the UV–visible spectra of the molecules. The analysis of the lowest spin-allowed (singlet-singlet) excited states divulged possible electronic transition. The o-substituted benzylideneaniline possessed the lowest highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) energy gap among the substituted and unsubstituted analogs. The intramolecular contacts were interpreted using natural bond orbital and localized molecular orbital analysis. The –CH=N– linkage was investigated as a bridge for the electron delocalization from the donor to acceptor moieties. The manifestation of a reduction peak in the cyclic voltammetric studies confirmed the electrochemical behavior in the –OH-substituted molecule, which was diffusion-controlled. The discrepancy in the electrochemical property concerning the position of the –OH substituent of the candidate molecules was put forward.

Polymeric hole transport materials (HTMs) have emerged because of their potential to produce dopant-free, efficient, and stable perovskite solar cells (PSCs). Therefore, we engineered 10 novel donor materials (SMH1–SMH10) containing phenanthrocarbazole-based polymeric structures for organic and PSCs. These molecules underwent bridging-core modifications using different spacers, such as furan (N1), pyrrole (N2), benzene (N3), pyrazine (N4), dioxane (N5), isoxazole (N6), isoindole (N7), indolizine (N8), double bond (N9), and pyrimidine (N10), in comparison to reference molecule R. The study examined the structure–property relationship and the impact of these modifications on the optical, photovoltaic, photophysical, and optoelectronic characteristics of the newly designed SMH1–SMH10 series. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations were conducted to analyze frontier molecular orbitals, density of states, reorganization energies, open-circuit voltage, transition density matrix, and charge transfer processes. Results show that the newly designed molecules (SMH1–SMH10) exhibited superior optoelectronics characteristics compared to the R molecule. Among these, SMH4 is the most promising candidate, with a small band gap (2.79 eV), low electron and hole mobility (λ_e 0.0028 eV, λ_h 0.0020 eV), lower binding energy (E_b 0.58 eV), high λ_max values (656.42 nm in gas, 573.34 nm in chlorobenzene), and a high V_oc of 1.30 V. Therefore, this study demonstrated that bridging-core modifications offer a simple and effective strategy for designing desirable characteristics molecules for photovoltaic applications.

Ketene 1,3-oxazoles and their derivatives present intriguing structures for the study of rotational barriers due to their pseudo–double-bond character stemming from resonance in the ketene moiety. A diverse range of compounds featuring this motif underwent quantum-chemical investigation to elucidate the nature of the stereochemical singularity observed in numerous cases. Because rotational barriers in most instances are too high to permit rapid interconversion, the findings are ascribed to thermodynamic rather than kinetic factors in the gas phase and within an implicit polar medium. The stabilities are attributed to internal hydrogen bonding where feasible. However, in cases where this is not possible, chalcogen bonding rather than steric effects governs the stereochemical preferences, particularly when S and Se comprise the heterocycle of these compounds. These findings hold promise for guiding the design of compounds whose properties hinge on stereochemistry and resonant structures, such as dyes.