Potential of B24O24 nanocluster for sensing and delivering chlormethine anticancer drug: a DFT study.

In the present research, the adsorption and release of chlormethine (CM) drug on the B24O24 nanocage have been reported in the water media and gas phase at GGA/PBE/DNP computational level. The interaction between B24O24 nanocage and CM drug shows that adsorptions of the chlormethine on B24O24 nanocage for the most stable complexes are - 1.47 to - 1.36 eV in the gas phase and water media, respectively. The CM adsorption caused a notable change in the band gap (Eg) and work function (Φ) of the B24O24 nanocage in the studied complexes. The binding of chlormethine to B24O24 also significantly increased the polarity of the drug carrier, which is a desirable property for drug delivery in biological environments. CM drugs can be released from the nanocage in the presence of an external electric field along the X-axis direction. The present study results show that the B24O24 nanocage is a possible carrier for delivering chlormethine drugs.

First-principles studies on two-dimensional B3O3 adsorbent as a potential drug delivery platform for TEPA anticancer drug.

The remarkable properties of pristine B3O3 nanosheet as a nanocarrier for adsorption and desorption of TEPA anticancer drug for designing potential drug delivery platform were investigated using periodic DFT calculations. We studied the adsorption energy of all stable complexes formed between the drug molecule and B3O3 in gas and aqueous phases along with electronic structure analysis of complexes. Different adsorption configurations were studied for drug/B3O3 complexes, including the interaction of the C atom of the triangular ring, O atom in the TEPA drug with the B atom in B3O3, and indirect drug interaction the middle of the R1 ring cavity of the B3O3 nanosheet. The take-up of TEPA prompts a substantial change of 68.13% in the band gap (Eg) of the B3O3 nanosheet in the most stable complex. The present study results affirmed the application of B3O3 nanosheet as a potential vehicle for TEPA drugs in the treatment of cancerous tissues.

Titanium-benzene complex as a molecular oxide adsorbent: a first principles approach.

CO, SO, NO, CO2, SO2, and NO2 gas sensing properties of Ti-benzene (C6H6Ti) complex are studied with first principles calculations by analyzing change in structural parameters, electronic properties, and charge transfer. Adsorption of all six oxide molecules on C6H6Ti complex is found to be thermodynamically favorable at ambient conditions. The Gibbs free energy-corrected adsorption energy range for oxide molecules is found be 0.6-5.9 eV. The SO2 transfers maximum charge to Ti metal, i.e., 0.36 (e-) as compare to other oxides. The binding energy of Ti atom to benzene ring remains higher even after adsorption of oxide gas molecules. The higher values of HOMO-LUMO gap show that oxide-adsorbed complexes are chemically stable. The ADMP-MD simulations show that all oxide molecules remain adsorbed on Ti-benzene complex during the simulations for the temperature range 300-500 K. The Ti-benzene complex shows considerable gas sensing properties at ambient conditions.

Toxic volatile organic compounds sensing by Al2C monolayer: A first-principles outlook.

Adsorption and detection performance of two-dimensional Al2C monolayer for four toxic volatile organic compounds (VOCs) viz. acetaldehyde, ethylene oxide, vinyl chloride, and benzene are investigated using first-principles calculations based on the periodic density functional theory. The band gap of Al2C nanosheet is changed substantially from 0.9 eV to 0.52, 1.41, 1.57, and 0.42 eV upon interaction with acetaldehyde, ethylene oxide, vinyl chloride, and benzene molecules respectively. The Al2C nanosheet maintains its semiconductor properties even after the adsorption of the four VOCs. The adsorption energy of four typical toxic volatile organic compounds (VOCs) viz. acetaldehyde, ethylene oxide, vinyl chloride, and benzene on the Al2C monolayer is in a range of -1.972 eV to -2.244 eV, which is higher than the adsorption energies obtained for several other VOCs adsorbed on different materials. Larger VOCs adsorption energies on Al2C monolayer obtained here may lead to adsorption of more VOC molecules on the material and consequently enhanced sensitivity. The results of ab initio molecular dynamics (AIMD) calculations for the studied complexes confirm their stability under the considered conditions of the simulation. Pristine Al2C monolayer might be a superior adsorbent and a promising sensing medium for toxic VOCs in real applications.

The potential application of borazine (B3N3)-doped nanographene decorated with halides as anode materials for Li-ion batteries: a first-principles study.

In this research, borazine-doped nanographene (BNG) decorated with halides as the anode material for Li-ion batteries (LIBs) has been investigated by means of first-principles calculations. The calculated adsorption energies of Li+/BNG and Li/BNG complexes are - 47.9 kcal/mol and - 25.2 kcal/mol, respectively, that gives electrochemical cell voltage (Vcell) of 0.99 V. To increase Vcell, different halide anions such as F-, Cl-, and Br- are added to BNG. This strategy increases Vcell from 0.99 V to 3.98, 1.54, and 1.62 V for BNG/F-, BNG/Cl-, and BNG/Br- complexes, respectively. The calculated Vcell value of 3.98 V for BNG/F- is remarkable compared with previous reports in the literature. The results presented in this study may be useful for the widespread usage of BNG/F- as a promising anode material for LIBs. Graphical abstract Note : This data is mandatory. Please provide.

Evaluation of one-dimensional potential energy surfaces for prediction of spectroscopic properties of hydrogen bonds in linear bonded complexes.

This work evaluated the reliability of the one-dimensional potential energy surface for calculating the spectroscopic properties (rovibrational constants and rotational line energies) of hydrogen bonds in linear bonded complexes by comparing theoretical results with the corresponding experimental results. For this purpose, two hydrogen bonded complexes were selected: the HCN···HCN homodimer and the HCN···HF heterodimer. The one-dimensional potential energy surfaces related to the hydrogen bonds in these complexes were calculated using different computational methods and basis sets. The calculated potential curve of each complex was fitted to an analytical one-dimensional potential function to obtain the potential parameters. The obtained analytical potential function of each complex was used in a two-particle Schrödinger equation to obtain the rovibrational energy levels of the hydrogen bond. Using the calculated rovibrational levels, the rovibrational spectra and constants of each complex were calculated and compared with experimental data available from the literature. Compared with experimental data, the calculated one-dimensional potential energy surface at the QCISD/aug-cc-pVDZ level of theory was found to predict the spectroscopic properties of hydrogen bonds better than the potential curves obtained using other computational methods, especially for the HCN···HCN homodimer complex. Generally, the results obtained for the HCN···HCN homodimer complex were closer to experimental data than those obtained for the HCN···HF heterodimer complex. The investigation performed in this work showed that the one-dimensional potential curve related to the hydrogen bond between two linear molecules can be used to predict the spectroscopic constants of hydrogen bonds. Graphical abstract Potential energy curves of HCN···HCN and HCN···HF complexes calculated at the different computational levels.

Tuning of chalcogen bonds by cation-π interactions: cooperative and diminutive effects.

The tunability of Y···N chalcogen bond via formation of a cation-π interaction in ternary complexes M(+)-PhYH-NH3, M(+)-PhYH-NCH, and M(+)-PhCCCN-YHF (M = Li, Na; Y = Se, Te) is investigated at MP2/aug-cc-pVDZ computational level. Our results indicate that the strength of Y···N and cation-π interactions in the ternary complexes depends on the role of the aromatic molecule. That is, a cooperative effect is evident if aromatic molecule acts as the Lewis acid and Lewis base, simultaneously, while a diminutive effect is observed when the aromatic molecule acts only as the Lewis base in both Y···N and cation-π interactions. For a given aromatic system, the shortening or lengthening of Y···N distances is more important for Li(+) complexes than Na(+) counterparts. The mechanism of cooperative/diminutive effects in the ternary complexes is studied by molecular electrostatic potential (MEP) and topological analysis of the electron density.

Effect of cooperativity in lithium bonding on the strength of halogen bonding and tetrel bonding: (LiCN)n···ClYF3 and (LiCN)n···YF3Cl (Y = C, Si and n = 1-5) complexes as a working model.

This paper reports results of cooperativity in lithium bonding on the strength of halogen bonding and tetrel bonding in complexes pairing CF3Cl and SiF3Cl with (LiCN)n complexes, where n varies from 1 to 5. Molecular geometries and stabilization energies of title complexes are calculated at the MP2 level with 6-311++G(d,p) basis set. Cooperative effects are found in terms of structural and energetic properties when lithium, halogen, and tetrel bonds are present in these complexes simultaneously. Our results reveal that strength of halogen and tetrel bondings are enhanced due to cooperativity of Li···N interactions in lithium bonded complexes. Good linear correlations between cooperativity parameters and electronic properties of complexes were established in the present study.

Rovibrational energy and spectroscopic constant calculations of complexes pairing via dihydrogen bonds.

In the present investigation, we performed a thorough study of potential energy curves, rovibrational spectra, and spectroscopic constants for complexes pairing via dihydrogen bonds. In particular, we dealt with LiH···HX (X = F, CN, CCH, CCF, CCCl) complexes by employing accurate electronic energy calculations at the MP2/aug-cc-pVDZ level of theory. Following this, the Numerov method was applied to solve the nuclear Schrödinger equation, thus obtaining spectroscopic constants and rovibrational spectra. Good linear correlation between the magnitudes of the interaction energies for interaction of HX with LiH, and the most positive electrostatic potentials of hydrogen in HX, was established.

Mutual influence between anion-π and pnicogen bond interactions: the enhancement of P⋯N and P⋯O interactions by an anion-π bond.

In this work, the interplay between anion-π and pnicogen bond interactions is investigated by ab initio calculations. Cooperative effects are observed in the studied complexes in which anion-π and pnicogen bond interactions coexist. These effects are analyzed in detail in terms of the energetic, geometric, charge-transfer and electron density properties of the complexes. The cooperative energy ranges from -1.8 to -4.1kcalmol(-1). The effect of an anion-π bond on a pnicogen bond is more pronounced than that of a pnicogen bond on an anion-π bond. The enhancing mechanism is analyzed in views with the charge-transfer, electrostatic potential and electron density analysis.

Mutual influence between conventional and unconventional lithium bonds.

The interplay between conventional and unconventional lithium bonds interactions in NCLi⋯NCLi⋯XCCX and CNLi⋯CNLi⋯XCCX (X=H, F, Cl, Br, OH, CH3, and OCH3) complexes is studied by ab initio calculations. Cooperative effects are observed when Li⋯N(C) and Li⋯π bonds coexist in the same complex. These effects are analyzed in terms of geometric, energetic and electron charge density properties of the complexes. The cooperative effects are larger in those complexes with shorter intermolecular distances than in those with the longest ones. The electron density at the lithium bond critical points can be regarded as a good descriptor of the degree of cooperative effects. An excellent linear correlation can be obtained between the cooperative energies and the calculated spin-spin coupling constants across the lithium bonds.

Characterization of halogen···halogen interactions in crystalline dihalomethane compounds (CH2Cl2, CH2Br2 and CH2I2): a theoretical study.

A theoretical study was performed to examine halogen···halogen (X···X) bonds properties in crystalline dihalomethane CH2X2 compounds (X=Cl, Br and I). MP2/aug-cc-pVTZ calculations reveal that the interaction energies for CH2X2 dimers lie in the range between -3.7 and -9.9 kJ mol(-1). One of the most important results of this study is that, according to symmetry-adapted perturbation theory, the X···X interactions are largely dependent on dispersion interactions. The contribution of electrostatic energy in the X···X interaction increases in the order Cl < Br < I, which is consistent with the greater amount of positive electrostatic potential on the halogen atom.

Theoretical study of the complementarity in halogen-bonded complexes involving nitrogen and halogen as negative sites.

This article analyzes the interplay between X···N and X···X halogen bonds interactions in NCX···NCX···XCH3 complexes, where X=Cl and Br. To better understand the properties of these systems, the corresponding dyads were also studied. These effects are studied theoretically in terms of geometric and energetic features of the complexes, which are computed by ab initio methods. The estimated values of cooperative energy (E coop) are all negative with much larger E coop in absolute value for the NCBr···NCBr···BrCH3 system. The effect of X···N on the properties of X···X is larger than that of X···X bonding on the properties of X···N. These results can be understood in terms of the electrostatic potentials of the negative sites with which the positive regions on the halogens are interacting. The nature of halogen bond interactions of the complexes is analyzed using parameters derived from the energy decomposition analysis.

Single electron pnicogen bonded complexes.

A theoretical study of the complexes formed by monosubstituted phosphines (XH2P) and the methyl radical (CH3) has been carried out by means of MP2 and CCSD(T) computational methods. Two minima configurations have been obtained for each XH2P:CH3 complex. The first one shows small P-C distances and, in general, large interaction energies. It is the most stable one except in the case of the H3P:CH3 complex. The second minimum where the P-C distance is large and resembles a typical weak pnicogen bond interaction shows interaction energies between -9.8 and -3.7 kJ mol(-1). A charge transfer from the unpaired electron of the methyl radical to the P-X σ* orbital is responsible for the interaction in the second minima complexes. The transition state (TS) structures that connect the two minima for each XH2P:CH3 complex have been localized and characterized.

Hydrogen bond strengthening of cis-trans glyoxal dimers in electronic excited states: a theoretical study.

The second-order approximate coupled-cluster (CC2) method was performed to investigate the excited state hydrogen-bonding properties of Glyoxal (C2H2O2, Gl) dimers. Since the strengthening and weakening of hydrogen bonds can be investigated by monitoring the vibrational absorption spectra of some hydrogen-bonded groups in different electronic states, the infrared spectra of the hydrogen-bonded Gl-Gl complexes in both of the ground state and the S1 electronically excited state are calculated using the MP2/CC2 methods respectively. We demonstrated that the intermolecular hydrogen bond C=O⋯H-C between two glyoxal molecules is significantly strengthened in the electronically excited S1 state upon photoexcitation of the hydrogen-bonded Gl-Gl complexes.

Cooperativity between fluorine-centered halogen bonds: investigation of substituent effects.

This article analyzes the substitution effects on cooperativity between fluorin-centered halogen bonds in NCF · · · NCF · · · NCX and CNF · · · CNF · · · CNX complexes, where X = H, F, Cl, CN, OH, and NH2. These effects are investigated theoretically in terms of geometric and energetic features of the complexes, which are computed by ab initio methods. The topological analysis, based on the quantum theory of atoms in molecules (QTAIM), is used to characterize the interactions and analyze their enhancement with varying electron density at bond critical points. It is found that the complexes with electron-donating groups exhibit a strong cooperativity, while a much weaker cooperativity occurs in the NCF · · · NCF · · · NCCN and CNF · · · CNF · · · CNCN trimers. An excellent correlation is found between the cooperative energy in the ternary complexes and the calculated three-body interaction energies. The energy decomposition analysis (EDA) indicates that the electrostatic and dispersion effects play a main role in the cooperativity of fluorine-centered halogen bonding.

Competition and interplay between the lithium bonding and hydrogen bonding: R3C···HY···LiY and R3C···LiY···HY triads as a working model (R=H, CH3; Y=CN, NC).

UMP2 calculations with aug-cc-pVDZ basis set were used to analyze intermolecular interactions in R3C···HY···LiY and R3C···LiY···HY triads (R=H, CH3; Y=CN, NC), which are connected via lithium and hydrogen bonds. To better understand the properties of these systems, the corresponding dyads were also studied. Molecular geometries and binding energies of dyads, and triads were investigated at the UMP2/aug-cc-pVDZ computational level. Particular attention was paid to parameters such as cooperative energies, and many-body interaction energies. All studied complexes, with the simultaneous presence of a lithium bond and a hydrogen bond, showed cooperativity with energy values ranging between −1.71 and −9.03 kJ mol−1. The electronic properties of the complexes were analyzed using parameters derived from atoms in molecules (AIM) methodology. Energy decomposition analysis revealed that the electrostatic interactions are the major source of the attraction in the title complexes.

A study of donor-acceptor in the charge transfer molecular complexes of some thiacrown ethers with dihalogen molecules by DFT method.

The molecular complexes of 1,3,5-trithiane, (TT), tetrathia-8-crown-4, (TT8C4), and trithia-9-crown-3 , (TT9C3) with dihalogens in the ground state were investigated in the gas and dicholoromethane phases using B3LYP method and 6-31G** and 6-31+G** bases sets. In both TT and TT8C4 complexes, it is predicted that charge transfer takes place from the dihalogen to the thiacrown ether molecule; the magnitude trend of the total CT was ICl > IBr > I2, and Cl2 > Br2 > I2, respectively. There was not such a trend with TT9C3. The frequency analysis showed that all complexes in the excited state were unstable. The analysis of natural bond orbitals and comparison of the calculated thermodynamic quantities of the complexes between the gas phase and tetrachloromethane solution confirmed the results.

Orthogonal interactions between nitryl derivatives and electron donors: pnictogen bonds.

Pnictogen complexes between nitryl derivatives (NO2X, X = CN, F, Cl, Br, NO2, OH, CCH, and C2H3) and molecules acting as Lewis bases (H2O, H3N, CO, HCN, HNC and HCCH) have been obtained at the MP2/aug-cc-pVTZ computational level. A total of 53 minima have been located. Their energy, geometry, DFT-SAPT energy terms, electronic properties (NBO, AIM, ELF, and NCI) and NMR shieldings have been calculated and analyzed. Finally, a search in the CSD database has been carried out, showing a large number of similar interactions in crystallographic structures.

Substituent effects on the cooperativity of halogen bonding.

DFT calculations (B97-1) with the 6-31+G(d,p)-LanL2DZdp basis set were used to analyze the intermolecular interactions in 4-Z-Py···XCN···XCN triads (Z = H, F, OH, OCH3, CH3, NH2, NO2, and CN; Py = pyridine; and X = Cl and Br) that are connected by halogen-bond interactions. To understand the properties of the systems better, the corresponding dyads are also studied. Particular attention is given to parameters such as cooperative energy. All complexes show cooperative energy ranging from -1.39 to -3.46 kJ mol(-1) and -2.61 to -5.84 kJ mol(-1) for X = Cl and Br, respectively. We show that the effect of the substituents on the title interactions strongly depends on the nature of the substituents (Z). Thus, the electron-donor and electron-acceptor substituents increase and decrease the stability of complexes, respectively. The electronic properties of the complexes have been analyzed using molecular electrostatic potential (MEP) and minimum average local ionization energy, and the parameters were derived from the atoms in molecules (AIM) and natural bond orbital (NBO) methodologies.