Facile preparation, characterization, SC-XRD and DFT/DTDFT study of diversely functionalized unsymmetrical bis-aryl-α, β-unsaturated ketone derivatives

A synthetic approach towards drug modification: 2-hydroxy-1-naphthaldehyde based imine-zwitterion preparation, single-crystal study, Hirshfeld surface analysis, and computational investigation

The current work is about the modification of primary amine functionalized drugs, pyrimethamine and 4-amino-N-(2,3-dihydrothiazol-2-yl)benzenesulfonamide, via condensation reaction with 2-hydroxy-1-naphthaldehyde to produce new organic zwitterionic compounds (E)-1-(((4-(N-(2,3-dihydrothiazol-2-yl)sulfamoyl)phenyl)iminio)methyl)naphthalen-2-olate (DSPIN) and (E)-1-(((4-amino-5-(4-chlorophenyl)-6-ethylpyrimidin-2-yl)iminio)methyl)naphthalen-2-olate (ACPIN) in methanol as a solvent. The crystal structures of both compounds were confirmed to be imine-based zwitterionic products via single-crystal X-ray diffraction (SC-XRD) analysis which indicated that the stabilization of both crystalline compounds is achieved via various noncovalent interactions. The supramolecular assembly in terms of noncovalent interactions was explored by the Hirshfeld surface analysis. Void analysis was carried out to predict the crystal mechanical response. Compound geometries calculated in the DFT (Density Functional Theory) study showed reasonably good agreement with the experimentally determined structural parameters. Frontier molecular orbital (FMO) analysis showed that the DSPIN HOMO/LUMO gap is by 0.15 eV smaller than the ACPIN HOMO/LUMO gap due to some destabilization of the DSPIN HOMO and some stabilization of its LUMO. The results of the charge analysis implied formation of intramolecular hydrogen bonds and suggested formation of intermolecular hydrogen bonding and dipole-dipole and dispersion interactions.

Benzimidazolium quaternary ammonium salts: synthesis, single crystal and Hirshfeld surface exploration supported by theoretical analysis

Owing to the broad applications of quaternary ammonium salts (QAS), we present the synthesis of benzimidazolium-based analogues with variation in the alkyl and alkoxy group at N-1 and N-3 positions. All the compounds were characterized by spectroscopic techniques and found stable to air and moisture both in the solid and solution state. Moreover, molecular structures were established through single-crystal X-ray diffraction studies. The crystal packing of the compounds was stabilized by numerous intermolecular interactions explored by Hirshfeld surface analysis. The enrichment ratio was calculated for the pairs of chemical species to acquire the highest propensity to form contacts. Void analysis was carried out to check the mechanical response of the compounds. Furthermore, theoretical investigations were also performed to explore the optoelectronic properties of compounds. Natural population analysis (NPA) has been conducted to evaluate the distribution of charges on the synthesized compounds, whereas high band gaps of the synthesized compounds by frontier molecular orbital (FMO) analysis indicated their stability. Nonlinear optical (NLO) analysis revealed that the synthesized QAS demonstrates significantly improved NLO behaviour than the standard urea.

Nonlinear Optical Properties and All Optical Switching of Curcumin Derivatives

In this work OR1(E1,6E) -1,7-bis (4-propyloxy phenyl) hepta-1,6-diene-3,5 dione compound is synthesized. The compound has been characterized via computational technique by studying the molecule's electronic structures through calculating its HOMO and LUMO energies, and its band gap energy (EHOMO-ELUMO). The nonlinear refractive index (NLRI) of the solution of OR1 compound in DMF solvent is determined using diffraction patterns (DPs) which resulted when a continuous wave laser beam of wavelength 473 nm traversed the compound solution in a glass cell of 1 mm thickness. By counting the number of rings under maximum beam input power, the NLRI of value 10- 6 cm2/W resulted. The NLRI is calculated once more via the Z-scan technique and a value of 0.25 × 10- 7 cm2/W is obtained. The vertical convection current in the OR1 compound solution appears to be responsible for the asymmetries noticed in the DPs. The temporal variation of each DP is noticed together with the evolution of DPs against beam input power. DPs are numerically simulated based on the Fresnel-Kirchhoff integral with good accord compared to the experimental findings. Dynamic and static all-optical switching in the OR1 compound using two laser beams (473 and 532 nm) is tested successfully.

Preparation, Crystal Structure, Supramolecular Assembly, and DFT Studies of Two Organic Salts Bearing Pyridine and Pyrimidine

The effective preparation of two new pyrimidine- and pyridine-based organic crystalline salts with substituted acidic moieties (i.e., (Z)-4-(naphthalen-2-ylamino)-4-oxobut-2-enoic acid (DCNO) and 2-hydroxy-3,5-dinitrobenzoic acid (PCNP)) using methanol as a solvent has been reported. These molecular salts have ionic interactions that are responsible for their structural stabilization in their solid-state assemblies. The crystal structures of DCNO and PCNP were determined by the single-crystal X-ray diffraction (SCXRD) technique. The SCXRD study inferred that cations and anions are strongly packed due to N-H···O, N-H···N, and C-H···O noncovalent interactions in DCNO, whereas in PCNP, N-H···N noncovalent interactions are absent. The noncovalent interactions in both organic crystalline salts were comprehensively investigated by Hirshfeld surface analysis. Further, a detailed density functional theory (DFT) study of both compounds was performed. The optimized structures of both compounds supported the existence of the H-bonding and weak dispersion interactions in the synthesized organic crystalline salt structures. Both compounds were shown to have large and noticeably different HOMO/LUMO energy gaps. The atomic charge analysis results supported the SCXRD and HSA results, showing the formation of intermolecular noncovalent interactions in both organic crystalline salts. The results of the natural bond orbital (NBO) analysis confirmed the existence of (relatively weak) noncovalent interactions between the cation and anion moieties of their organic crystalline salts. The global reactivity parameters (GRPs) analysis showed that both organic crystalline salts' compounds should be quite thermodynamically stable and that DCNO should be less reactive than PCNP. For both compounds, the molecular electrostatic potential (MEP) analysis results support the existence of intermolecular electrostatic interactions in their organic crystalline salts.

Quantum Chemical Exploration of A-π1-D1-π2-D2-Type Compounds for the Exploration of Chemical Reactivity, Optoelectronic, and Third-order Nonlinear Optical Properties

Organic compounds exhibit significant nonlinear optical (NLO) properties and can be utilized in various areas like optical parameters, fiber optics, and optical communication. Herein, a series of chromophores (DBTD1-DBTD6) with an A-π₁-D₁-π₂-D₂ framework was derived from a prepared compound (DBTR) by varying the structure of π-spacer and terminal acceptor. The DBTR and its investigated compounds were optimized at the M06/6-311G(d,p) level of theory. Frontier molecular orbitals (FMOs), nonlinear optical (NLO) properties, global reactivity parameters (GRPs), natural bonding orbital (NBO), transition density matrix (TDM), molecular electrostatic potential (MEP), and natural population analysis (NPA) were accomplished at the abovementioned level to describe the NLO findings. DBTD6 has the lowermost band gap (2.131 eV) among all of the derived compounds. The decreasing order of highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) energy gap values was DBTR > DBTD1 > DBTD2 > DBTD3 > DBTD4 > DBTD5 > DBTD6. The NBO analysis was carried out to describe noncovalent interactions such as conjugative interactions and electron delocalization. From all of the examined substances, DBTD5 showed the highest λ_max value at 593.425 nm (in the gaseous phase) and 630.578 nm (in chloroform solvent). Moreover, the β_tot and ⟨γ⟩ amplitudes of DBTD5 were noticed to be relatively greater at 1.140 × 10^-27 and 1.331 × 10^-32 esu, respectively. So, these outcomes disclosed that DBTD5 depicted the highest linear and nonlinear properties in comparison to the other designed compounds, which underlines that it could make a significant contribution to hi-tech NLO devices.

Synthesis, Structural, and Intriguing Electronic Properties of Symmetrical Bis-Aryl-α,β-Unsaturated Ketone Derivatives

Three symmetrical bis-aryl-α,β-unsaturated ketone derivatives, 2,6-di((E)-benzylidene)-cyclohexan-1-one (DBC), 2,6-bis((E)-4-chlorobenzylidene)cyclohexan-1-one (BCC), and (1E,1'E,4E,4'E)-5,5'-(1,4-phenylene)bis(2-methyl-1-phenylpenta-1,4-dien-3-one) (PBMP), have been prepared using the aldol condensation approach toward ketones having two enolizable sites. The structures of DBC, BCC, and PBMP have been resolved via spectrometric methods. Moreover, the crystal structure of PBMP is determined by the single-crystal X-ray diffraction (SC-XRD) technique, which revealed that the PBMP molecular assembly is stabilized by the intermolecular C-H···O bonding and C-O···π and weak T-shaped offset π···π stacking interactions. The Hirshfeld surface analysis (HSA) of the PBMP crystal structure was performed as well, and the results were compared with the results of DBC and BCC. The density functional theory (DFT) study results revealed that the longer conjugated molecule of PBMP has smaller but still quite significant HOMO-LUMO gaps compared to the smaller molecules of BCC and DBC. The natural population analysis (NPA) and natural bonding orbital (NBO) analysis were performed. Accordingly, the hydrogen bonding and dipole-dipole interactions stabilize the crystal structures of these compounds. Additionally, the NBO analysis showed numerous high-energy stabilizing interactions for the PBMP compound due to the presence of numerous delocalized and relatively easily polarizable π-electrons, thus implying its significant thermodynamic stability. According to the global reactivity parameter (GRP) analysis, the compounds BCC and DBC are relatively stable in redox processes and have high thermodynamic stability and relatively lower reactivity in general. The molecular electrostatic potential (MEP) analysis results imply potential formation of the intermolecular hydrogen bonding and dispersion interactions, which stabilizes the crystal structures of these compounds.

An Efficient Synthesis, Spectroscopic Characterization, and Optical Nonlinearity Response of Novel Salicylaldehyde Thiosemicarbazone Derivatives

In this study, seven derivatives of salicylaldehyde thiosemicarbazones (1-7) were synthesized by refluxing substituted thiosemicarbazide and salicylaldehyde in an ethanol solvent. Different spectral techniques (UV-vis, IR, and NMR) were used to analyze the prepared compounds (1-7). Accompanied by the experimental study, quantum chemical studies were also carried out at the M06/6-311G(d,p) level. A comparative analysis of the UV-visible spectra and vibrational frequencies between computational and experimental findings was also performed. These comparative data disclosed that both studies were observed to be in excellent agreement. Furthermore, natural bond orbital investigations revealed that nonbonding transitions were significant for the stability of prepared molecules. In addition, frontier molecular orbital (FMO) findings described that a promising charge transfer phenomenon was found in 1-7. The energies of FMOs were further used to determine global reactivity parameters (GRPs). These GRP factors revealed that all synthesized compounds (1-7) contain a greater hardness value (η = 2.1 eV) and a lower softness value (σ = 0.24 eV), which indicated that these compounds were less reactive and more stable. Nonlinear optical (NLO) evaluation displayed that compound 5 consisted of greater values of linear polarizability ⟨α⟩ and third-order polarizability ⟨γ⟩ of 324.93 and 1.69 × 105 a.u., respectively, while compound 3 exhibited a larger value of second-order polarizability (βtotal) of 508.41 a.u. The NLO behavior of these prepared compounds may be significant for the hi-tech NLO applications.

Synthesis, antioxidant, antimicrobial and antiviral docking studies of ethyl 2-(2-(arylidene)hydrazinyl)thiazole-4-carboxylates

A series of ethyl 2-(2-(arylidene)hydrazinyl)thiazole-4-carboxylates (2a-r) was synthesized in two steps from thiosemicarbazones (1a-r), which were cyclized with ethyl bromopyruvate to ethyl 2-(2-(arylidene)hydrazinyl)thiazole-4-carboxylates (2a-r). The structures of compounds (2a-r) were established by FT-IR, ¹H- and ¹³C-NMR. The structure of compound 2a was confirmed by HRMS. The compounds (2a-r) were then evaluated for their antimicrobial and antioxidant assays. The antioxidant studies revealed, ethyl 2-(2-(4-hydroxy-3-methoxybenzylidene)hydrazinyl)thiazole-4-carboxylate (2g) and ethyl 2-(2-(1-phenylethylidene)hydrazinyl)thiazole-4-carboxylate (2h) as promising antioxidant agents with %FRSA: 84.46 ± 0.13 and 74.50 ± 0.37, TAC: 269.08 ± 0.92 and 269.11 ± 0.61 and TRP: 272.34 ± 0.87 and 231.11 ± 0.67 μg AAE/mg dry weight of compound. Beside bioactivities, density functional theory (DFT) methods were used to study the electronic structure and properties of synthesized compounds (2a-m). The potential of synthesized compounds for possible antiviral targets is also predicted through molecular docking methods. The compounds 2e and 2h showed good binding affinities and inhibition constants to be considered as therapeutic target for M^pro protein of SARS-CoV-2 (COVID-19). The present in-depth analysis of synthesized compounds will put them under the spot light for practical applications as antioxidants and the modification in structural motif may open the way for COVID-19 drug.

Tuning the optoelectronic properties of oligothienyl silane derivatives and their photovoltaic properties

Four new Donor-Acceptor (D-A) type oligothiophenes based structures (C1-C4) were designed by substituting different acceptors moieties around tetrahedral silicon core to simulate their photovoltaic properties. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) quantum analysis were carried out to reconnoiter various parameters of solar cells. A comparative analysis has conducted between designed structures and reference molecule R to conclude our simulated results. Among all the structures, C2 has displayed highest absorption values (380 nm) with red shift and minimum band gap (Δ_H-L) of 4.11 eV in dichloromethane at DFT-CAM-B3LYP/6-31G (d,p) using IEFPCM model. The C2 has also shown the lowest values of electron reorganization energy (λe = 0.018eV) and hole reorganization energy (λh = 0.015eV) therefore, could be suggested for use in organic solar cells because of its most noteworthy charge carrier mobilities. Again, C2 has the different trend in TDM graph because the electron density is present in the lower right part of core unit and in the acceptor moiety due to high electron affinities of end capped acceptor having cyanide groups.

Coumaronochromone as antibacterial and carbonic anhydrase inhibitors from Aerva persica (Burm.f.) Merr.: experimental and first-principles approaches

The Aerva plants are exceptionally rich in phytochemicals and possess therapeutics potential. Phytochemical screening shows that Aerva persica (Burm.f.) Merr. contains highest contents i.e., total phenolics, flavonoids, flavonols, tannins, alkaloids, carbohydrates, anthraquinones and glycosides. In-vitro antibacterial and enzymatic (carbonic anhydrase) inhibition studies on methanol extracts of A. persica indicated the presence of biological active constituents within chloroform soluble portions. Investigation in the pure constituents on the chloroform portions of A. persica accomplished by column chromatography, NMR and MS analysis. The bioguided isolation yields four chemical constituents of coumaronochromone family, namely aervin (1-4). These pure chemical entities (1-4) showed significant antibacterial activity in the range of 60.05-79.21 µg/ml against various bacterial strains using ampicillin and ciprofloxacin as standard drugs. The compounds 1-4 showed promising carbonic anhydrase inhibition with IC₅₀ values of 19.01, 18.24, 18.65 and 12.92 µM, respectively, using standard inhibitor acetazolamide. First-principles calculations revealed comprehensive intramolecular charge transfer in the studied compounds 1-4. The spatial distribution of highest occupied and lowest unoccupied molecular orbitals, ionization potential, molecular electrostatic potential and Hirshfeld analysis revealed that these coumaronochromone compounds would be proficient biological active compounds. These pure constituents may be used as a new pharmacophore to treat leaukomia, epilepsy, glaucoma and cystic fibrosis.

An Experimental and Computational Exploration on the Electronic, Spectroscopic, and Reactivity Properties of Novel Halo-Functionalized Hydrazones

Herein, halo-functionalized hydrazone derivatives "2-[(6'-chloroazin-2'-yl)oxy]-N'-(2-fluorobenzylidene) aceto-hydrazone (CPFH), 2-[(6'-chloroazin-2'-yl)oxy]-N'-(2-chlorobenzylidene) aceto-hydrazones (CCPH), 2-[(6'-chloroazin-2'-yl)oxy]-N'-(2-bromobenzylidene) aceto-hydrazones (BCPH)" were synthesized and structurally characterized using FTIR, 1H-NMR, 13C-NMR, and UV-vis spectroscopic techniques. Computational studies using density functional theory (DFT) and time dependent DFT at CAM-B3LYP/6-311G (d,p) level of theory were performed for comparison with spectroscopic data (FT-IR, UV-vis) and for elucidation of the structural parameters, natural bond orbitals (NBOs), natural population analysis, frontier molecular orbital (FMO) analysis and nonlinear optical (NLO) properties of hydrazones derivatives (CPFH, CCPH, and BCPH). Consequently, an excellent complement between the experimental data and the DFT-based results was achieved. The NBO analysis confirmed that the presence of hyper conjugative interactions was pivotal cause for stability of the investigated compounds. The energy gaps in CPFH, CCPH, and BCPH were found as 7.278, 7.241, and 7.229 eV, respectively. Furthermore, global reactivity descriptors were calculated using the FMO energies in which global hardness revealed that CPFH was more stable and less reactive as compared to BCPH and CCPH. NLO findings disclosed that CPFH, CCPH, and BCPH have superior properties as compared to the prototype standard compound, which unveiled their potential applications for optoelectronic technology.

Exploration of Noncovalent Interactions, Chemical Reactivity, and Nonlinear Optical Properties of Piperidone Derivatives: A Concise Theoretical Approach

The organic compounds with a π-bond system lead to electric charge delocalization which enables them to reveal fascinating nonlinear optical properties. Mono-carbonyl curcuminoids also have an appealing skeleton from the conjugation view point. Interesting chemical structures of the 3,5-bis(arylidene)-N-benzenesulfonyl-4-piperidone derivatives motivated us to perform density functional theory (DFT)-based studies. Therefore, computations using the B3LYP/6-311G(d,p) functional of DFT were executed to explore geometric parameters, highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energies, and natural bond orbital (NBO) analyses. Moreover, three different functionals such as HF, B3LYP, and M06 with the 6-311G(d,p) basis set were used to investigate the average polarizability ⟨α⟩ and first hyperpolarizability (β_tot)-based properties of all compounds. A good concurrence among calculated and experimental parameters was obtained through root mean square error calculations. The molecular stability of piperidone derivatives was examined using the Hirshfeld surface and NBO analyses. Natural population analysis was also performed to obtain insights about atomic charges. Calculated HOMO-LUMO energies showed that charge transfer interactions take place within the molecules. Moreover, global reactivity parameters including electronegativity, chemical hardness, softness, ionization potential, and electrophilicity were calculated using the HOMO and LUMO energies. The average polarizability ⟨α⟩ and first hyperpolarizability (β_tot) values of all compounds were observed to be larger in magnitude at the aforesaid functional than the standard compound.