IR Peak Research Articles

In situ infrared absorption spectroscopy of cryogenic-specific reddish coloration produced by cryoplasma irradiation on an ice surface

Recently, cryoplasma has been demonstrated to form reddish coloration on methanol- and water-containing ice surfaces below 150 K. This cryogenic-temperature-only reddish coloration could provide a clue for understanding the composition of the red organic materials observed in the outer solar system. In this study, ice with reddish coloration was analyzed by IR absorption spectroscopy (2500–1700 cm−1) during cryoplasma irradiation at 85 K and subsequent increase of the temperature from 85 to 200 K without cryoplasma. The intensities of the IR peaks, differing from those of the raw materials, increased with the irradiation time during reddish coloration. When the reddish coloration disappeared at 120–150 K, the IR peak intensities at 2170 and 1790 cm−1 decreased. These peaks are thought to originate from C- and/or N-containing triple bonds or cumulative double bonds and carbonyl groups. Therefore, the reddish materials are considered to contain these functional groups.

Elucidating the adsorption of 2-Mercaptopyridine drug on the aluminum phosphide (Al12P12) nanocage: A DFT study

Adsorption amplitude of the aluminum phosphide (Al12P12) nanocage toward the 2-Mercaptopyridine (MCP) drug was herein monitored based on density functional theory (DFT) calculations. The adsorption process through MCP⋅⋅⋅Al12P12 complex in various configurations was elucidated by means of adsorption (Eads) energies. According to the energetic affirmations, the Al12P12 nanocage demonstrated potential versatility toward adsorbing the MCP drug within the investigated configurations and exhibited significant negative adsorption energies up to −27.71 kcal/mol. Upon the results of SAPT analysis, the electrostatic forces showed the highest contributions to the overall adsorption process with energetic values up to −74.36 kcal/mol. Concurrently, variations of molecular orbitals distribution along with alterations in the energy gap (Egap) and Fermi level (EFL) of the studied nanocage were denoted after adsorbing the MCP drug. The favorable impact of water solvent within the MCP⋅⋅⋅Al12P12 complexes was unveiled and confirmed by negative solvation energy (ΔEsolv) values up to −17.75 kcal/mol. According to thermodynamic parameters, the spontaneous and exothermic natures of the considered adsorption process were proclaimed by negative values of ΔG and ΔH parameters. Significant changes in the IR and Raman peaks, along with the appearance of new peaks, were noticed, confirming the occurrence of the targeted adsorption process. Furthermore, the adsorption features of the MCP drug on the Al12N12 nanocage were elucidated and compared to the Al12P12 analog. The obtained results demonstrated the higher preferability of Al12P12 nanocage than the Al12N12 candidate towards adsorbing the MCP drug without structural distortion.

Detection of germanium isotopes in biosynthesized Ge nanocrystals through different optical spectroscopy techniques

The current work aims to investigate the isotopic effect in biosynthesized Germanium nanocrystals (Ge NCs) through Raman and IR absorption spectra. By treating bulk germanium crystal with microorganisms in a weak magnetic field, Ge NCs with great chemical and isotopic purity are produced on its surface. Using various techniques, including X-ray diffraction, photoluminescence spectroscopy, micro-Raman spectroscopy, and FTIR spectroscopy, the structural and optical characteristics of the synthesized Ge NCs are studied. The PL, Raman, and IR peaks of synthesized material, which are recorded at various time intervals, are seen to have shifted. The PL peak shift of fabricated material is seen as a result of the quantum confinement effect. Raman and IR absorption spectra analysis, which are conducted at room temperature reveals the possible presence of germanium isotopes. It is observed that the phonon absorption peaks of synthesized germanium NC material shift to longer wavelengths with increasing average atomic mass of germanium. The observed optical properties of the synthesized Ge NCs have provided great help to study the change in structural and optical properties of the synthesized Ge crystal.

Locally Enhanced Electric Field Treatment of E. coli: TEM, FT-IR and Raman Spectrometry Study

In this paper, we report the study of the low-voltage locally enhanced electric field treatment (LEEFT) of E. coli bacteria via TEM analysis and FT-IR and Raman spectrometry. The formation of pores was confirmed by TEM, which revealed the membrane rupture along with the formation of precipitates in the membrane and the cell volume, and by photoluminescence spectra of propidium iodide dye. LEEFT results in the alternation of DNA and RNA structure, indicated by the change in its α-helical and β-helical forms, decrease and narrowing of the nucleic acids-related IR and Raman peaks. Membrane damage is illustrated by the ambiguous character after low-voltage exposure: several membrane fatty acids’ peaks are broadening, while the others narrow, which indicates the overall change of the molecular bonds in their moiety, and may result from the rigidification during the shrinkage of the inner membrane and the increase in fluidity of the outer membrane. The corresponding fingerprints of cytochrome c and bo, located in the membrane or in the periplasm, on Raman spectra, reflect the arising changes in their structure and moiety. The observed changes were partially confirmed by TEM images, which indicate the dense precipitates’ formation in the cell volume and membrane, as well as the cytoplasmic membrane shrinkage away from the outer membrane.

Energy gap tuning, ferromagnetic switching, visualization of electron density and bonding in dilute magnetic semiconductor Fe-doped SnO2

Low-cost, high-yield dilute magnetic semiconductor FexSn1−xO2 with x = 0.025, 0.05, 0.075 compositions were synthesized by a one-step chemical precipitation method at room temperature. XRD analysis reveals a tetragonal rutile structure with little orthorhombic SnO2 and Sn metal phase. The optical bandgap is tunable from 3.51 eV to 2.2 eV by Fe doping, and the composition Fe0.075Sn0.925O2 has maximum optical absorption with a minimum energy gap of 2.2 eV, beneficial for optical applications. Magnetic switching from paramagnetism to soft ferromagnetism at room temperature is revealed with Fe doping with ultra-low coercivity useful for DMS applications. In addition to the strong photoluminescent blue peak reported by most authors, a moderate IR peak at 717 nm is observed in this work, which is attributed by the presence of Fe2+ ions. The cation (Sn/Fe) deficiency analysis using the Rietveld method shows a gradual decrease from 3.5% to 1.5%, which will be the primary cause of the photoluminescent emissions. Electronic structure reveals apical Sn/Fe-O strong covalent bonding and moderate Sn/Fe-O equatorial ionic bonding tendency, which are the favourable conditions for ferromagnetism in Fe-doped SnO2. Higher electron density at non-nuclear maxima (NNM) points shows the defect mechanism, which enhances the photoluminescence and energy gap reduction.

Synthesis, Characterization, and Antimicrobial and Nematicidal Activities of Chitosan-Based Silver-Doped Titanium Dioxide.

Chitosan (Cs)-based silver-doped titanium dioxide (Cs-AgTiO2) films were synthesized intending their end-use application in food packaging. AgTiO2 NPs were successfully prepared by using electrochemical synthesis. Cs-AgTiO2 films were synthesized by using the solution casting technique. Various advanced instrumental techniques such as scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR) were used for the characterization of Cs-AgTiO2 films. Intending their food packaging applications, samples were further investigated to obtain varied biological results including antibacterial (Escherichia coli), antifungal (Candida albicans), and nematicidal activities. Ampicillin (E. coli) and fluconazole (C. albicans) were used as models. FT-IR and XRD confirm the structural modification of Cs. IR peak shifting was observed, which confirmed that AgTiO2 interacted with chitosan via amide I and amide II groups. This confirmed the stability of the filler in the polymer matrix. SEM also confirmed the successful incorporation of AgTiO2 NPs. Cs-AgTiO2 (3%) shows excellent antibacterial (16.51 ± 2.10 μg/mL) and antifungal (15.67 ± 2.14 μg/mL) activities. Nematicidal assays were also done, and Caenorhabditis elegans (C. elegans) was used as a model organism. Cs-AgTiO2 NPs (3%) exhibited excellent nematicidal potential (64.20 ± 1.23 μg/mL), which could make these films a suitable novel material to control nematode spread in food.

Synthesis, structural and spectral investigations of an optically active E-N′-(3,4-dimethoxybenzylidene)− 4-fluorobenzohydrazide crystal

Hydrazines represent a group of compounds with pronounced pharmacological activities, along with their possible use of optically active materials. In this contribution, E-N′-(3,4-dimethoxybenzylidene)− 4-fluorobenzohydrazide (DBF) was synthesized and chemically characterized by X-ray crystallography, IR, Raman, UV–VIS, and NMR spectroscopies. The intermolecular interactions governing the stability of the crystal were investigated by the Hirshfeld surface analysis. The structure optimization was performed starting from a crystallographic one. The highest resemblance between experimental and theoretical bond lengths and angles was obtained for the structure at M06–2X/6–311 + +G(d,p) level of theory. The Natural Bond Orbital (NBO) and Quantum Theory of Atoms in Molecules (QTAIM) analyses outlined the most important intramolecular interactions. The IR and Raman spectra vibrational peaks were assigned based on the Potential Energy Distribution (PED) analysis. Theoretical methods with high correlation factors and low mean absolute error reproduced the NMR chemical shifts. The excited state optimization of DBF with a difference of several nm modelled the peak at 330 nm in the experimental UV–VIS spectrum. The Condensed Fukui functions outlined the most active positions for electrophilic, neutrophilic, and radical attacks. The non-linear optical (NLO) Z-scan experiment determined the absorption coefficient and nonlinear refractive index, concluding that DBF can be used as NLO material. The ECOSAR prediction of toxicity showed that the material could be potentially dangerous for aquatic organisms.

Characterization of Eri Silk Fabrics Dyed with Fermented Banana Trunk Bio-Extract

ABSTRACT This research aims to study the characterization of Eri silk fabrics dyed with fermented banana trunk bio-extract (FBTBe). The ratios of FBTBe to water were 25:75, 50:50 and 75:25 (v/v) at 30, 60 and 90 minutes for dyeing. The result revealed when the amount of FBTBe increased, the yellow value increased. Moreover, Eri silk fabrics processed with dyeing times at 60 and 90 minutes at 75:25 concentration were found to have the highest value of yellow (p ≤ .05). The colorfastness to washing with soap test found that the color change in all concentration ratios at the 60 minutes, more than 3.00. The colorfastness to perspiration test found the color change value of the dyed Eri silk fabrics was an acceptable value of more than 3.00. As for the colorfastness to hot pressing test, all treatments showed that the mean color change values more than 3.00. Moreover, the tearing strength, the results demonstrated that the Eri silk fabrics processed with all conditions were not significantly when compared with pre-dyed Eri silk (p > .05). The functional groups of the dyed Eri silk were investigated using FTIR. The results revealed no differences in the characteristic IR peaks of functional groups present in all treatments.

2D BN-biphenylene: structure stability and properties tenability from a DFT perspective.

With state-of-the-art density functional theory and ab initio molecular dynamics, we explored the BN-analog of a recently synthesized 2D biphenylene sheet. Its dynamical, thermal, and mechanical stability has been confirmed with phonon spectrum calculations, ab initio molecular dynamics (AIMD), and Born criteria, and its synthesis feasibility has been ascertained in terms of cohesive energy. The phonon spectrum and AIMD results show all positive frequencies and negligible variations in structure (bond length), kinetic and total energy for 5 ps, respectively. Having found this stable BN-BPh, we have analyzed its electronic, mechanical, optical, and vibration properties. Electronic property results (density of states and band structure) show that the BN-equivalent of metallic BPh has a large band gap of 3.12 eV and 4.48 eV with the PBE and HSE06 DFT functionals, respectively, similar to the graphene BN-equivalent (hBN) with a band gap of 6.1 eV. The mechanical strength of BN-BPh is close to that of BPh with a difference of ∼15 N m-1 and ∼10 N m-1 along the x- and y-directions, and its Young's modulus indicates that BN-BPh is stiffer than BN-graphyne. The optical absorption coefficient of BN-BPh shows a first peak at 4.48 eV (3.12 eV) with the HSE06 (PBE) functional. Infrared and Raman spectrum intensity and irreducible representation are computed, and the first IR (Raman) peak is found at 1300 cm-1 (1000 cm-1) for BN-BPh. Finally, substitutions of external atoms such as P, Al, As, C, Li, Mg, S, and Si for B and N atoms in BN-BPh tune its electronic properties to semiconducting, semi-metallic, and even metallic. Considering its mechanical, optical, and band gap tunability, BN-BPh might be useful in electronic, optical, and spintronics devices, even in high-pressure environments.

Infrared Diffusion‐Ordered Spectroscopy Reveals Molecular Size and Structure**

AbstractInspired by ideas from NMR, we have developed Infrared Diffusion‐Ordered Spectroscopy (IR‐DOSY), which simultaneously characterizes molecular structure and size. We rely on the fact that the diffusion coefficient of a molecule is determined by its size through the Stokes–Einstein relation, and achieve sensitivity to the diffusion coefficient by creating a concentration gradient and tracking its equilibration in an IR‐frequency resolved manner. Analogous to NMR‐DOSY, a two‐dimensional IR‐DOSY spectrum has IR frequency along one axis and diffusion coefficient (or equivalently, size) along the other, so the chemical structure and the size of a compound are characterized simultaneously. In an IR‐DOSY spectrum of a mixture, molecules with different sizes are nicely separated into distinct sets of IR peaks. Extending this idea to higher dimensions, we also perform 3D‐IR‐DOSY, in which we combine the conformation sensitivity of femtosecond multi‐dimensional IR spectroscopy with size sensitivity.

Infrared Diffusion-Ordered Spectroscopy Reveals Molecular Size and Structure.

Inspired by ideas from NMR, we have developed Infrared Diffusion-Ordered Spectroscopy (IR-DOSY), which simultaneously characterizes molecular structure and size. We rely on the fact that the diffusion coefficient of a molecule is determined by its size through the Stokes-Einstein relation, and achieve sensitivity to the diffusion coefficient by creating a concentration gradient and tracking its equilibration in an IR-frequency resolved manner. Analogous to NMR-DOSY, a two-dimensional IR-DOSY spectrum has IR frequency along one axis and diffusion coefficient (or equivalently, size) along the other, so the chemical structure and the size of a compound are characterized simultaneously. In an IR-DOSY spectrum of a mixture, molecules with different sizes are nicely separated into distinct sets of IR peaks. Extending this idea to higher dimensions, we also perform 3D-IR-DOSY, in which we combine the conformation sensitivity of femtosecond multi-dimensional IR spectroscopy with size sensitivity.

Microwave Assisted Synthesis of a Novel Schiff Base Scaffolds of Pyrazole Nuclei: Green Synthetic Method

Aim: The research aims to develop a sustainable microwave-assisted scheme for Synthesizing 5-(benzylidene amino)-1-phenyl-1H-pyrazole-4-carbonitrile congeners. Background: 5-(benzylideneamino)-1-phenyl-1H-pyrazole-4-carbonitrile scaffolds are novel molecules having various pharmacological activities such as neurodegenerative, anti-microbial, anticancer. Schiff base congeners are considered as efficient pharmacophores for research. These activities are due to the presence of azomethine (CH=N) group in the Schiff base compounds. Objectives: To synthesise different novel Schiff base compounds of pyrazole nuclei by green chemistry with a decent yield. Methods: The 5-(benzylideneamino)-1-phenyl-1H-pyrazole-4-carbonitrile scaffolds were prepared by two-step reactions. Both steps were microwave-assisted. The first step was to synthesize 5- amino-1-phenyl-1H-pyrazole-4-carbonitrile as an intermediate compound. This compound was synthesized by using phenyl hydrazine and 2-(ethoxymethylene)malononitrile. The temperature, pressure, and time required for this reaction were 102°C, 300W, and 45 minutes respectively. In the second step, the final Schiff base congeners were attained by reacting this compound with several aromatic aldehydes. The yield, reaction condition, and time consumption were all acceptable for the green synthetic methods rather than the conventional schemes. Results: The microwave-assisted method was more efficient. The reactions were less timeconsuming, and the overall yield of the all-synthesized compounds was 75-82%. Different spectroscopic methods characterized the synthesized congeners. The IR peak is considered the main functional group (azomethine) at 1611 cm-1 wavelength. Conclusions: This microwave-assisted synthetic scheme thus appears more environmentally due to a significant reduction in organic solvents, resulting in fewer hazardous residues. Using this scheme, we prepared different Schiff base congeners with satisfactory chemical yields.

Geochemical anomalies caused by meteorite impact and volcanism at the Cretaceous-Paleogene boundary, Wasserfallgraben (Lattengebirge, Germany)

The Cretaceous-Paleogene (K/Pg) mass extinction is the only major mass extinction event that is known to be related to a major meteorite impact (Chicxulub, Mexico) and also occurred during major flood basalt eruptions (Deccan Traps, India). Here, we present geochemical proxies for impact and volcanism analysed in the same sediment samples from the deep-marine sedimentary record of the Gosau Group spanning the K/Pg boundary at Wasserfallgraben, Germany. We measured major and trace elements, including iridium (Ir), tellurium (Te), mercury (Hg), total organic carbon (TOC), and organic carbon isotopes (δ13Corg) on 33 samples from 2 m below to 1.36 m above the K/Pg boundary, a timespan of ∼260 ka. Results show an undisturbed profile, confirmed by changes in calcareous nannofossils assemblages, with a sharp positive Ir peak (2.3 ppb) at the K/Pg boundary (0–10 cm, 25 cm). Volcanic proxies (Hg/TOC, Te/Th) show three distinct peaks not corresponding to the Ir peak, suggesting a volcanic origin, and higher values in the earliest Danian. Compared to the profile in Bidart the proxies of volcanism are less intense in our profile, indicating that the “Deccan Signal” is either diluted or not present in some locations worldwide. The time recorded in the sampled sediments is short (∼0.26 Ma) compared to Deccan flood basalt eruptions (∼1 Ma), but elevated Hg/TOC and Te/Th ratios in the Danian sediments suggests the impact happened prior to the main volcanic outgassing of the Deccan Traps. Our results support the hypothesis that the impact might have triggered the largest, rapidly-erupted Deccan lava formations.

Recovery of lithium from high Mg/Li ratio salt-lake brines using ion-exchange with NaNTf2 and TBP

In view of the complex problems for the ionic liquids (ILs) recovery with the system containing ILs and TBP, this work proposed a NaNTf2-based synergistic extraction system, NaNTf2 + TBP, which could realize the effective reutilization of the extraction system without reducing the lithium separation ability. Under the optimal extraction parameters, the extraction efficiency of Li+ exceeded 98%, while that of Mg2+ was only ~1%. The results of mass spectrometry (ESI-MS) and slope analysis showed that two TBP molecules involved in the extraction process of Li+, and the Li+ extraction mechanism obeyed the cation-exchange process. According to the red shift of the FT − IR peak of PO in TBP and the chemical shift changes of P in 31P NMR, the interaction strength between TBP and different metal ion followed the sequence: ETBP−H >> ETBP−Li > ETBP−Mg > ETBP−K > ETBP−Na. It was also found that after a three−stage countercurrent extraction process, [Li+]org was 0.42 g L−1, and the total recovery efficiency of Li+ was about 98%. The saturated extraction capacity for Li+ could be as high as 5.4 g L−1, and Li+ could be stripped with the aqueous solution containing 0.2 mol L-1 HCl. In addition, the extraction efficiency of Li+ was almost not attenuated after 6 extraction cycles. This new extraction system shows a certain industrial application prospect for Li+ separation from the salt lake bine with high Mg/Li ratio.

Biodegradation of Low- and High-Density Polyethylene Films by Microbacterium Barkeri Sh20

Polyethylene waste contamination is one of the most concerning environmental issues not only in India but also in world. Microbial degradation is one of the safest and environment friendly process to degrade polyethylene among other major types degradation methods such as thermo-oxidative degradation and photo-degradation. The present research focused on the isolation, enrichment, and characterization of polyethylene-utilizing bacteria, not screen as far for biodegradation, and evaluation of its degrading capacity on polyethylene. A bacterial strain (TN2) was isolated from a motor-oil contaminated soil. The biochemical characterization of the strain was based on an automated microbial identification system. Strain TN2 was identified through 16SrRNA gene sequencing, which shows strain was closely related to Microbacterium genus and identified as Microbacterium barkeri SH20 (Accession No. KY887791.1). To examine the degradation capacity of isolated strain, it was used for biodegradation studies on two types of polyethylene films i.e. LDPE as well as HDPE (low and high density polyethylene respectively) HDPE (high-density polyethylene) for 30 days. The film samples were analyzed after bacterial strain incubation based on the weight loss percentage and the Keto & Ester Carbonyl Index (via Fourier transform infrared spectroscopy- FTIR). The highest decrease in weight loss percentage was calculated of PE-S1 HDPE film samples i.e 0.985±0.23%, as weight loss represents a qualitative evaluation of biodegradation. FTIR studies shows changes IR peaks of C=O regions and Keto & Ester Carbonyl Index was found to decrease in HDPE films (PE-S1) compared to other two LDPE (PE-S2) and HDPE films (PE-S3) shows degradation of polyethylene. The research established that Microbacterium barkeri SH20 (TN2) is a novel bacterial strain that can degrade polyethylene films. Hence, it can be used in future biodegradation studies and field trails.

Effect of Clubbell Training on Glenohumeral Internal and External Rotation, Muscle Function, and Ball Velocity in Baseball Pitchers

OBJECTIVES This study examined the effects of clubbell exercises in a pitcher training program on the range of motion (ROM), muscle function, and its subsequent influence on pitching velocity. Additionally, this study aimed to develop an optimal training program to prevent injury while improving pitcher performance.METHODS Eighteen pitchers were included and equally divided into clubbell exercise and control groups. Clubbell training was conducted through 60-minute sessions twice a week for 12 weeks. Internal/external rotational (IR/ER) ROM, IR/ER muscle strength, muscle endurance, muscle power, and pitching velocity were measured before and after the intervention.RESULTS The IR (<i>p</i> = 0.051) and total ROM (TROM; <i>p</i> = 0.05) of the throwing arm decreased in the control group but increased in the clubbell exercise group, with an observed tendency of interaction. In the non-throwing arm, the ER ROM was significantly different between the two groups (<i>p</i> <0 .05), also with an observed tendency of interaction (<i>p</i> = 0.055). IR peak torque per body weight at 60°/sec significantly increased in both groups over the exercise period (<i>p</i> < 0.01). Total work per body weight and average power of IR at 180°/sec increased in both groups over the exercise period (<i>p</i> < 0.01). The pitching velocity decreased in both groups throughout the exercise period (<i>p</i> < 0.05).CONCLUSIONS Although 12 weeks of clubbell training had limited effects on ROM, the findings revealed that this exercise could be effective in improving pitching performance, preventing injuries, and maintaining long-term performance. Further studies are recommended for a more detailed assessment.

Synthesis and quantum mechanical characterization of three new 1-(5-nitro-benzimidazole-2′-yl-sulfonyl-acetyl)- 4-aryl-thiosemicarbazide with biological potential

The paper contains the results obtained in grafting the acyl-thiosemicarbazide on the holder molecule 5-nitro-benzimidazol-2-sulfonyl-acetic acid by oxidation reaction of 5-nitro-benzimidazol-2-yl-mercapto-acetic acid, then passed to the corresponding sulfonyl hydrazide. Acyl-thiosemicarbazides containing the sulfonyl group were obtained. The chemical structure of the newly obtained compounds was confirmed by spectral analysis (FT-IR, 1H-NMR). This article aims with spectral and quantum-chemical characterization of three new thiosemicarbazides with potential tuberculostatic action. The reaction way, the main IR and NMR peaks and the quantum-mechanical parameters, computed with Spartan’14 program are estimated. The tuberculostatic of action is analyzed compared with reference drug isoniazid.

FORMULATION AND EVALUATION OF FLOATING TABLET OF THIOCOLCHICOSIDE

Thiocolchicoside is a centrally acting analgesic and is used to treat moderate to severe pain. Thiocolchicoside is rapidly and almost completely absorbed after oral administration, showing good bioavailability. Hence the main objective of the work was to design, development and in vitro evaluation of natural gum based matrix tablet of Thiocolchicoside. All the batches were evaluated for angle of repose, carr’s index, hausner’s ratio, hardness, thickness, weight variation, drug content and in vitro release characteristics. The results of DSC and IR spectroscopy exhibited that no chemical interaction between drug and polymers and no shifting in the IR peaks was observed. The release kinetics and the mechanism of drug release by regression coefficient analysis were investigated. The optimized tablets having HPMC provided more sustained drug release than other polymers. The drug release from the tablets was sufficiently sustained and non-Fickian transport of the drug from tablets was confirmed. KEYWORDS: Thiocolchicoside, HPMC K15M, Carbopol 934P, MCC PH102.

Microwave-assisted Synthetic Scheme of Novel Schiff Base Congeners of Pyrimidine Nuclei by Using Water as Solvent: A Green Approach to Synthesis

Aim: The research work aims to develop a sustainable microwave-assisted scheme for the synthesis of 4-(benzylidene amino)-6-phenylpyrimidine-5-carbonitrile congeners. Background: 4-(benzylidene amino)-6-phenylpyrimidine-5-carbonitrile scaffolds are novel molecules having various pharmacological activities, such as neurodegenerative, antimicrobial, and anticancer. Schiff base congeners are considered efficient pharmacophores for research. These activities are due to the presence of azomethine (CH=N) group in the Schiff base compounds. Objectives: The aim of the study was to synthesise different novel Schiff base scaffolds of pyrimidine nuclei by green chemistry in good yield. Methods: The 4-(benzylidene amino)-6-phenylpyrimidine-5-carbonitrile scaffolds were prepared by two-step reactions. Both steps were microwave-assisted. The first step was to synthesize 4-amino-6- phenylpyrimidine-5-carbonitrile as an intermediate compound. This compound was synthesized by using benzaldehyde, malononitrile and formamidine hydrochloride. The reaction conditions are as follows: temperature- 101°C, pressure- 300W, time- 50min. The final Schiff base congeners were obtained by reacting them with various aromatic aldehydes in the second step. The yield, reaction condition, and time consumption were all very acceptable for the green synthetic methods rather than the conventional schemes. Results: Microwave-assisted method was more efficient. The reactions were less time-consuming, and the overall yield of the all-synthesized compounds was in the range of 72-81%. The synthesized congeners were characterized by different spectroscopic methods. The main functional group, azomethine, was considered by the IR peak at 1611 cm-1 wavelength. Conclusions: This microwave-assisted synthetic method thus emerges as more eco-friendly due to a much-reduced usage of organic solvents, leading to less harmful residues. Using this scheme, we synthesized different Schiff base congeners with satisfactory chemical yields.

IR spectra of [formula omitted] in Ar and [formula omitted] cryomatrices: Evidence of unusual band splitting in [formula omitted] matrix

Matrix isolation IR spectra of CH2I2 in N2 matrix are analysed using IR spectra obtained in the Ar matrix, quantum chemical calculations, and molecular point group symmetry to determine the origin of the unusual splitting observed in the CH2 antisymmetric stretching (ν6), CH2 rocking (ν7), CH2 wagging (ν8), and CI2 antisymmetric stretching (ν9) modes of CH2I2 only in N2 matrix and not in Ar matrix. The ν6, ν7, ν8, and ν9 vibrational modes belong to either B1 or B2 irreducible representations under C2V point group symmetry. IR spectra in N2 matrix is reported for the first time. IR spectra recorded in Ar matrix are consistent with previous reports. Electronic structure calculations have been performed to obtain simulated IR spectra of CH2I2 with C2V and C2 point group symmetries, (CH2I2)2 conformers, [CH2I2-H2O], and [CH2I2-(N2)4]. IR spectra obtained in Ar and N2 matrices originate from CH2I2, (CH2I2)2, and splitting of IR peaks in N2 matrix. Splitting of the IR peaks of CH2I2 in solid state is described by Davydov splitting or factor group splitting. The observed splitting of IR peaks in N2 matrix is due to the lowering of symmetry of CH2I2 from C2V to one of its sub groups due to the perturbation of the rigid N2 matrix that possess quadrupole moment.