Acetonitrile Solvent Research Articles

The solvation effect of photochromic nonlinear optical properties switch

In 2009, the interesting photochromic complex o-MeCN and its isomeric close form c-MeCN were synthesized and investigated, which would transform to each other according to the characterization of UV and visible irradiation. In our work, the excellent nonlinear optical (NLO) properties are obtained by theoretical calculating. Results show that the βtot value of c-MeCN is about 12 times as large as that of o-MeCN in acetonitrile solvent, which provide a basis for NLO switch. Further, the UV–visible absorption spectrum can confirm that the remarkable βtot values for c-MeCN are mainly attributed to the charge transfer induced by the photocyclization. Significantly, the βtot values reduced with the increasing of dielectric constant ε of the solvent, and the differences of βtot values between the open and close form, present a regularly change in different solvents. This reversible photochromic process and solvent effect may open up new opportunities for the discovery of attractive NLO switch.

Simultaneous determination of macrolides in water samples by solid-phase extraction and capillary electrophoresis.

Solid-phase extraction (SPE) coupled with capillary electrophoresis (CE) for the determination of macrolide antibiotics (azithromycin, clarithromycin, roxithromycin, tylosin) and tiamulin in water samples was described in this article. These compounds were extracted with different types of sorbents ( Oasis HLB, C18, C8, SDB, and Strata-X) and different masses of sorbents (60 mg, 200 mg, and 500 mg) using different organic solvents (methanol, ethanol, and acetonitrile) and different pH values of water samples (pH 7.00, 8.00, and 9.00). It was found that the highest extraction efficiency of the studied compounds was obtained with 200 mg/3 mL C18 cartridges with methanol as eluent at pH 9.00 of the water sample. The developed SPE-CE method for macrolide antibiotics and tiamulin was validated for linearity, precision, repeatability, the limit of detection (LOD), the limit of quantification (LOQ), and recovery. Good linearity was obtained in the range of 0.3-30 mg L-1 depending on the drug, with correlation coefficients higher than 0.9958 in all cases except clarithromycin (0.9873). Expanded measurement uncertainties were calculated for each pharmaceutical, accounting for 20.31 % (azithromycin), 38.33 % (tiamulin), 28.95 % (clarithromycin), 26.99 % (roxithromycin), and 21.09 % (tiamulin). Uncertainties associated with precision and calibration curves contributed the most to the combined measurement uncertainty. The method was successfully applied to the analysis of production waste-water from the pharmaceutical industry.

Anodic Dissolution of Al in KOH Solutions in the Mixed Ethanol–Acetonitrile Solvent

Anodic Dissolution of Al in KOH Solutions in the Mixed Ethanol–Acetonitrile Solvent

Fe-Ni bimetallic supported on mordenite catalyst for selective oxidation of veratryl alcohol in a continuous reactor

Veratryl alcohol (VA) is preferentially oxidized to veratraldehyde (VADE) using a heterogeneous catalyst, which is more favoured in industries. Commercial mordenite (Ca,Na2,K2) Al2Si10O24·7H2O) was desilicated with NaOH and loaded with nickel and iron bimetal by the wet impregnation method. The synthesised Mordenite-Fe(5 %)/Ni(5–20 %) bimetallic catalyst, possessing active Bronsted acid sites, was employed to selectively oxidize the veratryl alcohol reaction. FT-IR, XRD, BET, HR-SEM, HR-TEM, and TPD were employed to determine the catalyst's textural attributes, morphology, chemical properties, and stability. Selective oxidation was performed over the catalysts using TBHP as an oxidant in a continuous reactor. To examine the most active catalyst among the four and to maximise the conversion and yield, the reaction conditions are optimised for various reaction parameters The reaction conditions were optimized by attaining 100 % conversion at temperature (90° C) for time (2 hr) and a maximum conversion of 97 % and a selectivity of 99 % at 10 bar pressure, WHSV (1.0 h−1) with acetonitrile solvent. The result of the study display that Fe (5 %) and Ni(15 %) impregnated on mordenite exhibits excellent catalytic stability with conversion (100 %) and selectivity (99 %) among the other catalysts. During regeneration, the conversion rate declined from 99.5 to 92.4.7 % and selectivity declined from 100 % to 96.2 % at the end of the seventh cycle. The high selectivity and stability of MOR-Fe(5 %)/Ni(15 %) imply that they might function properly as appropriate catalysts for the oxidation of aromatic alcohols. The advantages of the current synthesis are its cost-efficiency and eco-friendliness.

Synchronous or stepwise Mechanism? a theoretical study on the Excited-State double proton transfer properties of shikonin and acetylshikosin

The excited state double proton transfer (ESDPT) mechanism of shikonin (Shk) and its derivative acetylshikosin (AcShk) were studied by density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods. The potential energy curves scanned along the coordinates of proton transfer indicate a preference for the ESDPT reaction to occur step by step. The AcShk molecule possesses an additional reaction pathway in comparison to the Shk molecule. Furthermore, efforts have been made to compute the absorption and fluorescence peak, which exhibits favorable conformity with the experimental findings of the system investigated. The fluorescence spectra in cyclohexane and acetonitrile solvents indicate that the solvent polarity affects the location of the ESDPT fluorescence peak in both Shk and AcShk systems. The fluorescence spectra concentrated in the green light region (504 nm ∼ 550 nm) are obtained, which has the potential to promote human health through disinfection and boosting the immune system.

Determination of self-diffusion coefficients in mixtures with benchtop 13C NMR spectroscopy via polarization transfer.

Nuclear magnetic resonance (NMR) is an established method to determine self-diffusion coefficients in liquids with high precision. The development of benchtop NMR spectrometers makes the method accessible to a wider community. In most cases, 1H NMR spectroscopy is used to determine self-diffusion coefficients due to its high sensitivity. However, especially when using benchtop NMR spectrometers for the investigation of complex mixtures, the signals in 1H NMR spectra can overlap, hindering the precise determination of self-diffusion coefficients. In 13C NMR spectroscopy, the signals of different compounds are generally well resolved. However, the sensitivity of 13C NMR is significantly lower than that of 1H NMR spectroscopy leading to very long measurement times, which makes diffusion coefficient measurements based on 13C NMR practically infeasible with benchtop NMR spectrometers. To circumvent this problem, we have combined two known pulse sequences, one for polarization transfer from 1H to the 13C nuclei (PENDANT) and one for the measurement of diffusion coefficients (PFG). The new method (PENPFG) was used to measure the self-diffusion coefficients of three pure solvents (acetonitrile, ethanol and 1-propanol) as well as in all their binary mixtures and the ternary mixture at various compositions. For comparison, also measurements of the same systems were carried out with a standard PFG-NMR routine on a high-field NMR instrument. The results are in good agreement and show that PENPFG is a useful tool for the measurement of the absolute value of the self-diffusion coefficients in complex liquid mixtures with benchtop NMR spectrometers.

Preparation and characterization of ball milled hexagonal‑boron nitride (BMBN) and fluorescein (FL) decorated reduced graphene oxide (RGO) nanocomposite towards toxic heavy metal ion detection

In the present work, a novel hybrid fluorescent nanocomposite (RBF) based on ball milled hexagonal-Boron Nitride (BMBN) and Fluorescein (FL) decorated reduced Graphene Oxide (RGO) was synthesized for the effective detection and removal of hazardous heavy metal ions present in effluents. Where two different textile effluents namely, reaction outlet and factory outlet collected at the river Noyyel, Tamilnadu were considered. The prepared RBF was subjected to XRD, FTIR, SEM, EDX, TEM, PSA, BET, UV–vis, PL and XPS studies which strongly confirm the decoration of FL and BMBN at the surface of RGO sheets. The selectivity of RBF was examined by considering various toxic heavy metal ions. Where the RBF exhibits remarkable sensing towards Zn2+ (10.7 nM) via enhanced fluorescence and for Fe3+ (15.6 nM), Sn4+ (60.7 nM) and Hg2+ (465.4 nM) ions by “Turn-off” fluorescence only at neutral pH. In addition, the RBF was highly efficient to remove Hg (81.3 %) than Zn (63.7 %), Fe (38.2 %) and Sn (62.9 %) in real-time samples. Moreover, the prepared RBF could also serve as water sensor for the water contaminated organic solvents of Acetonitrile (ACN) and Tetrahydrofuran (THF). Hence the prepared RBF might be a potential choice for the effective detection and removal of heavy metal ions during wastewater treatment.

Improved sample introduction approach in hydrophilic interaction liquid chromatography to avoid breakthrough of proteins

When therapeutic proteins are analysed under hydrophilic interaction liquid chromatography (HILIC) conditions, there is an inherent mismatch between the sample diluent (proteins must be solubilised in aqueous media) and the mobile phase, which is mostly composed of aprotic solvent (acetonitrile). This difference in eluent strength between sample diluent and mobile phase is responsible for severe analyte breakthrough and peak distortion. As demonstrated with therapeutic proteins of different sizes (insulin of 6 kDa, anakinra of 17 kDa and rituximab subunits of 25 and 50 kDa), only very small volumes of 0.1–0.2 µL can be injected without breakthrough effects, when performing rapid analysis on short HILIC columns of 20–50 mm, leading to poor sensitivity. In order to avoid the undesired effect of the strong sample diluent, a special injection program should be preferred. This consists in the addition and automatic injection of a defined volume of weak solvent (acetonitrile) along with the sample to increase retention factors during sample loading. Various injection programs were tested, including the addition of a pre-injection or post-injection or both (bracketed injection) of acetonitrile plugs. Several weak to strong injection solvent ratios of 1:1, 1:2, 1:4 and 1:10 were tested. Our work proves that the addition of a pre-plug solvent with a weak vs. strong injection solvent ratio of 1:10 is a valuable strategy to inject relatively large volumes of proteins in HILIC, regardless of column dimensions, thus maximising sensitivity. No peak deformation or breakthrough was observed under these conditions. However, it is important to note that peak broadening (40 % larger peaks) was observed when the injection program increased the injection solvent ratio from 1:1 to 1:10. Finally, this strategy was applied to a wide range of therapeutic mAb products with different physico-chemical properties. In all cases, relatively large volumes can be successfully injected onto small volume HILIC columns using a purely aqueous sample diluent, as long as an appropriate (weak) solvent pre-injection is applied.

Enhancing the Cation-Binding Ability of Fluorescent Calixarene Derivatives: Structural, Thermodynamic, and Computational Studies.

Novel fluorescent calix[4]arene derivatives L1 and L2 were synthesized by introducing phenanthridine moieties at the lower calixarene rim, whereby phenanthridine groups served as fluorescent probes and for cation coordination. To enhance the cation-binding ability of the ligands, besides phenanthridines, tertiary-amide or ester functionalities were also introduced in the cation-binding site. Complexation of the prepared compounds with alkali metal cations in acetonitrile (MeCN), methanol (MeOH), ethanol (EtOH), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO) was investigated at 25 °C experimentally (UV spectrophotometry, fluorimetry, microcalorimetry, and in the solid state by X-ray crystallography) and by means of computational techniques (classical molecular dynamics and DFT calculations). The thermodynamic parameters (equilibrium constants and derived standard reaction Gibbs energies, reaction enthalpies, and entropies) of the corresponding reactions were determined. The tertiary-amide-based compound L1 was found to have a much higher affinity toward cations compared to ester derivative L2, whereby the stabilities of the ML1+ and ML2+ complexes were quite solvent-dependent. The stability decreased in the solvent order: MeCN ≫ EtOH > MeOH > DMF > DMSO, which could be explained by taking into account the differences in the solvation of the ligands as well as free and complexed alkali metal cations in the solvents used. The obtained thermodynamic quantities were thoroughly discussed regarding the structural characteristics of the studied compounds, as well as the solvation abilities of the solvents examined. Molecular and crystal structures of acetonitrile and water solvates of L1 and its sodium complex were determined by single-crystal X-ray diffraction. The results of computational studies provided additional insight into the L1 and L2 complexation properties and structures of the ligands and their cation complexes.

Determination of naproxen in mixtures of water and an organic solvent based on chemiluminescence of reaction mixtures containing europium ions

A simple and sensitive method, based on chemiluminescence of a reaction system containing europium(III) ions, for determination of naproxen in mixed solvents of water and an organic solvent (methanol, ethanol, 1-propanol, 1-butanol and acetonitrile) is proposed. Organic solvents are often used in the preliminary procedures of sample preparation for determination of active ingredients. The method is based on chemiluminescence accompanying naproxen oxidation by Ce(IV) ions in the environment of sulfuric acid, sensitized with europium(III) ions. This environment ensures stable and reproducible conditions of measurements in water and mixed solvents. In such a system a linear relation was observed between the integrated intensity of chemiluminescence in the spectral range λ > 585 nm and naproxen concentration in the range from 6 × 10−8 molL−1 to 6 × 10−6 molL−1, and with the limit of detection of 1.5 × 10−8 molL−1 (0.004 μg/mL). The relation is described by the same linear equation in water and in mixed solvent of water and 0.1–20 % (v/v) of an organic solvent. The method is characterized by high tolerance of the presence of foreign substances, including other nonsteroid anti-inflammatory drugs (NSAIDs). The proposed method has been successfully used for determination of naproxen in pharmaceutical formulations and samples of human urine subjected to preliminary treatment with alcohol or acetonitrile.

Tailoring Ag Electron Donating Ability for Organohalide Reduction: A Bilayer Electrode Design.

Electrochemical reduction of organohalides provides a green approach in the reduction of environmental pollutants, the synthesis of new organic molecules, and many other applications. The presence of a catalytic electrode can make the process more energetically efficient. Ag is known to be a very good electrode for the reduction of a wide range of organohalides. Herein, we examine the elementary adsorption and reaction steps that occur on Ag and the changes that result from changes in the Ag-coated metal, strain in Ag, solvent, and substrate geometry. The results are used to develop an electrode design strategy that can possibly be used to further increase the catalytic activity of pure Ag electrodes. We have shown how epitaxially depositing one to three layers of Ag on catalytically inert or less active support metal can increase the surface electron donating ability, thus increasing the adsorption of organic halide and the catalytic activity. Many factors, such as molecular geometry, lattice mismatches, work function, and solvents, contribute to the adsorption of organic halide molecules over the bilayer electrode surface. To isolate and rank these factors, we examined three model organic halides, namely, halothane, bromobenzene (BrBz), and benzyl bromide (BzBr) adsorption on Ag/metal (metal = Au, Bi, Pt, and Ti) bilayer electrodes in both vacuum and acetonitrile (ACN) solvent. The different metal supports offer a range of lattice mismatches and work function differences with Ag. Our calculations show that the surface of Ag becomes more electron donating and accessible to adsorption when it forms a bilayer with Ti as it has a lower work function and almost zero lattice mismatch with Ag. We believe this study will help to increase the electron donating ability of the Ag surface by choosing the right metal support, which in turn can improve the catalytic activity of the working electrode.

Probing and Evaluating the Anion Binding Effects in One‐Walled meso‐Phenylboronic Acid Appended Calix[4]pyrrole (C4P) Based Supramolecular Receptors

AbstractHerein, binding affinities of one‐walled meso‐phenylboronic acid functionalized calix[4]pyrroles (C4Ps, 3 a & 3 b) with diverse anions including spherical, linear, trigonal, and tetrahedral through UV‐Vis spectroscopy have successfully been revealed in acetonitrile solvent. The C4P derivative 3 b was newly synthesized from an easily accessible 3‐acetylphenylboronic acid via both conventional as well as green protocols. Structure of the final compound 3 b and the dipyrromethane (DPM) 2 b, were unambiguously established by means of 1H‐NMR, 13C‐NMR, and HRMS spectral data. From the outcomes of the UV‐Vis titrations of 3 a/3 b with different anions (e. g., F−, Cl−, Br−, I−, NO3−, HSO4−, H2PO4−, CH3COO−, & SCN−), used as their tetrabutylammonium (TBA) salts in CH3CN, 1 : 1 stoichiometric binding mode were observed from the BindFit v0.5 and Job plots. Overall, the binding affinity of receptor (3 b) with different anions were found higher in comparison to the receptor (3 a), presumably due to more cooperative NH and/or OH hydrogen bonding interactions. On the basis of varied size of halide ions, typical trend of anion binding affinity i. e., F−>Cl−>Br−>I−, was detected with increase in size of halide ions from F− to I−. Hopefully, these anion binding investigations with C4P‐based meso‐functionalized architectures will open new possibilities to the researchers to generate even more interesting artificial anion receptors based on vital boronic acid functionality, as biological and chemical importance of the anions is continuously motivating the synthetic chemists worldwide.

Monomer and Excimer Emission in Electrogenerated Chemiluminescence of Pyrene and 2,7-Di-tert-butylpyrene Associated with Electron Transfer Distance.

Electrogenerated chemiluminescence (ECL) is a light emission phenomenon caused by electrochemically generated radical anions (R•-) and cations (R•+), in which the ion annihilation results in the formation of a pair of excited (R*) and ground state (R) of a luminescent molecule. Here, the ECL properties of pyrene (Py) and 2,7-di-tert-butylpyrene (di-t-BuPy) are reported. It was found that at a commonly employed concentration (1 mM), the ECL spectra were time-dependent because of increasing the oligomer emission and increasing the concentration of R near R*, leading to an enhancement of the excimer emission. At a low concentration range (20-30 μM), the shape of the ECL spectra containing the monomer and excimer emission was determined by isolated pairs of R* and R, which were generated through ion annihilation of R•- and R•+. It was found that in the ECL of Py and di-t-BuPy originated from the isolated pairs of R•- and R•+, 58 and 48% of the excited states were the excimer states, respectively. Diffusion equation analysis indicates that the lower excimer formation in the case of di-t-BuPy is because of a farther initial separation distance between R* and R, i.e., a longer electron transfer distance between the radical ions. The Marcus model for the electron transfer kinetics suggests that the farther electron transfer distance is mainly caused by the larger molecular size, which resulted in a smaller reorganization energy of the solvent acetonitrile molecule. Taking advantage of the photophysical and electrochemical properties of Py and di-t-Bu Py, the monomer and excimer emission in ECL is discussed.

Desolvation Processes in Channel Solvates of Niclosamide.

The antiparasitic drug niclosamide (NCL) is notable for its ability to crystallize in multiple 1:1 channel solvate forms, none of which are isostructural. Here, using a combination of time-resolved synchrotron powder X-ray diffraction and thermogravimetry, the process-induced desolvation mechanisms of methanol and acetonitrile solvates are investigated. Structural changes in both solvates follow a complicated molecular-level trajectory characterized by a sudden shift in lattice parameters several degrees below the temperature where the desolvated phase first appears. Model fitting of kinetic data obtained under isothermal heating conditions suggests that the desolvation is rate-limited by the nucleation of the solvent-free product. The desolvation pathways identified in these systems stand in contrast to previous investigations of the NCL channel hydrate, where water loss by diffusion initially yields an anhydrous isomorph that converts to the thermodynamic polymorph at significantly higher temperatures. Taking the view that each solvate lattice is a unique "pre-organized" precursor, a comparison of the pathways from different starting topologies to the same final product provides the opportunity to reevaluate assumptions of how various factors (e.g., solvent binding strength, density) influence solid-state desolvation processes.

Crystals of Ni6L12 Ellipsoidal Tubes as Single-Crystal-to-Single-Crystal Adsorption Matrix: Penetrative Study of Self-Assembled Crystals vs Guest-Exchanged Crystals.

Informative similarities/differences between self-assembled and single-crystal-to-single-crystal (SCSC) guest-exchanged crystals based on both the molecular structure and adsorption nature are observed. The self-assembly of Ni(ClO4)2 with a dicyclopentyldi(pyridine-3-yl)silane bidentate ligand (L) in a mixture of toluene and acetonitrile gives rise to purple crystals consisting of double-stranded ellipsoidal tubes, [Ni6(ClO4)4(CH3CN)8L12]·8ClO4·4CH3CN·5C7H8. The coordinated acetonitriles as well as the solvates are removed at 170 °C to transform the purple crystals into blue crystals of [Ni(ClO4)2L2]n that return to the original crystals in the mixture of toluene and acetonitrile. Further, the toluene and acetonitrile solvates of the original crystals are replaced by o-, m-, and p-xylene isomers within 5 min in a SCSC manner. In the present study, SCSC xylene-exchanged crystals were compared with crystals obtained from direct self-assembly in a mixture of each xylene isomer and acetonitrile.

Use of QM/MM Surface Hopping Simulations to Understand Thermally Activated Rare-Event Nonadiabatic Transitions in the Condensed Phase.

We implement a rare-event sampling scheme for quantifying the rate of thermally activated nonadiabatic transitions in the condensed phase. Our Quantum mechanics/molecular mechanics (QM/MM) methodology uses the recently developed Interface for NonAdiabatic QM/MM in Solvent (INAQS) package to interface an elementary electronic structure package and a popular open-source molecular dynamics software (GROMACS) to simulate an electron transfer event between two stationary ions in a solution of acetonitrile solvent molecules. Nonadiabatic effects are implemented through a surface hopping scheme, and our simulations allow further quantitative insight into the participation ratio of a solvent and the effect of ion separation distance as far as facilitating electron transfer. We also demonstrate that the standard gas-phase approaches for treating frustrated hops and velocity reversal must be refined when working in the condensed phase with many degrees of freedom. The code and methodology developed here can be easily expanded upon and modified to incorporate other systems and should provide a great deal of new insight into a wide variety of condensed phase nonadiabatic phenomena.

Synthesis of biochar modified with 12-tungstophosphoric acid for the selective conversion of isoeugenol to vanillin

A heterogeneous acid catalyst was synthesized by anchoring 12–tungstophosphoric acid (HPW) onto biochar derived from Brazil nut shells (Bertholletia excelsa). This catalyst was used for the synthesis of vanillin from isoeugenol, employing hydrogen peroxide in acetonitrile solvent. The HPW-functionalized biocatalyst was prepared using a sonication method, which avoids the need for toxic and corrosive solvents, effectively incorporating tungsten at a mass proportion of 25%. Characterization of the catalysts utilized various techniques, including X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and ultraviolet–visible spectroscopy. 30HPW/CC(200–2) exhibited high selectivity for vanillin (55%) with a significant conversion rate (69%). Over four cycles, selectivity and conversion remained consistently above 56% and 45%, respectively. The results presented in this study have the potential to promote a more sustainable vanillin production process, a valuable additive in the food and perfume industries, renowned for its high economic value.

Solvent Engineering of Hole‐Transport Layer for Improved Efficiency and Stability in Perovskite Solar Cells

Although perovskite solar cells (PSCs) are one of the fastest‐growing photovoltaic technologies, many innovations are required to further improve performance and stability. The acetonitrile (ACN) solvent used to dissolve the Li‐TFSI salt in Spiro‐OMeTAD corrodes the perovskite thin film. In this study, 1‐methoxy‐2‐propanol (1MEO) and 2‐ethoxy‐ethanol (2ETO) solvents are used by replacing ACN. The utilization of 1MEO results in improved hole mobility in Spiro‐OMeTAD and reduction in defects at the perovskite/Spiro‐OMeTAD interface, thus diminishing nonradiative recombination. The recombination resistances in the low‐frequency range are determined via electrochemical impedance spectroscopy (EIS) and are found to be 3361.9 ohms for ACN‐Spiro‐OMeTAD, 4406.8 Ω for 1MEO‐Spiro‐OMeTAD, and 3815.3 Ω for 2MEO‐Spiro‐OMeTAD. These results indicate that the utilization of 1MEO and 2ETO instead of ACN effectively decreases charge recombination in PSCs. As a result, after replacing ACN with 1MEO and 2ETO, PSCs achieve a power conversion efficiency (PCE) of 21.3% and 20.0% respectively, while a PCE of 18.9% is obtained from the control device with ACN. During 45 d stability test, the initial efficiency of the control device decreases by 31.2%, while the 1MEO and 2ETO devices exhibit efficiency reductions of 12.2% and 7.7%, respectively.

Theoretical study on mechanism of benzene to phenol over VAPO-5 molecular sieve

The impact of the active site produced by the active metal V centre on the production of phenol from benzene was deduced from the cluster model structure of VAPO-5. In this work, the mechanism of benzene to phenol under the VAPO-5 model was explored. The transition states, intermediates, and reaction energy barrier throughout the reaction were evaluated by the ONIOM approach, which combines semi-empirical analysis with density functional theory. The outcomes demonstrated that this reaction was divided into four stages, with each stage's energy barriers being 59.9, 122, 204.8, and 60.7 kJ/mol, respectively. And a lower energy barrier of 204.8 kJ/mol must be surpassed to pass the determining speed phase's energy barrier of 296.8 kJ/mol. Additionally, the solvation of acetonitrile was looked into, resulting in the crossing of the energy barrier of 174.8 kJ/mol.

Rational design of co-ordination compounds in combination of bipyridine type of ligands and group 7 metal (M = Mn, Re) for photoCORM: a DFT study.

A large number of manganese and rhenium tricarbonyl complexes are known in literature along with various applications in different fields. CO-releasing molecules (CORMs) got recent research attention because CO can act as a prodrug for different diseases. CORMs offer the promising prospect of a safe and controllable amount of CO release. In this research work, we have explored the electronic properties of compounds such as bipyridine-related [Mn(CO)3] and [Re(CO)3] and we have compared the electronic properties of both manganese and rhenium tricarbonyl complexes in the light of carbon monoxide releasing tendency. The chosen Mn and Re metals have enough possibility to vary or play with ligands and design a new and novel CORM molecule. In this context, we have taken a range of 4,4'-disubstituted 2,2' bipyridyl ligands (Rbpy, where R = NH2, tBu, OCH3, H, CF3, CN, NO2) to investigate CO's liberation ability to identify and study such molecules. The calculated absorbance of designed complexes (1-14) shows visible/near-IR region (350-850 nm). The HOMO-LUMO energy gap of 7 (ΔE=2.40 eV) complex and for complex 14 (ΔE=2.28 eV) which is lesser in all complexes but the MLCT percentage is greater in Mn tricarbonyl complexes in comparison to Re tricarbonyl complexes. The calculated results of the FMO approach revealed that complex 7 and 14 have the lowest energy gap which is also in good agreement with DOSs and TDM results. The theoretically calculated results revealed that the both Mn and Re tricarbonyl complexes have a tendency for labialization of CO, but Mn tricarbonyl complexes are more prone to CO release because they have higher MLCT percentage. In this research work, we have performed density functional theory (DFT) calculations to explore the physical properties of compounds such as bipyridine-related [Mn(CO)3] and [Re(CO)3] and we have compared the physical properties of both manganese and rhenium tricarbonyl complexes in the light of carbon monoxide releasing tendency. DFT-based calculations were performed by using B3LYP/LANL2DZ basis set followed by acetonitrile solvent using the conductor-like polarizable continuum model (CPCM) for different calculations. Various geometrical calculations were performed using the Gaussian16 suite of programs and the output results obtained from Gaussian16 were visualized using GaussView 5.0.16. The same level of theory was used for various calculations, including frontier molecular orbital (FMO) analysis, metal to ligand charge transfer (MLCT), density of state (DOS) calculations, and transition density of matrix (TDM) calculations. For specific calculations, GaussSum 2.2 software package was used to calculate the density of states, and the Multiwfn 3.8 program was used to analyze the transition density matrix, which is presented using heat maps for both electrons and holes.