Search Results (59)

Accurate determination of carbon core-electron binding energies (C1s CEBEs) is crucial for X-ray photoelectron spectroscopy (XPS) assignments and predictive computational modeling. This study evaluates density functional theory (DFT)-based methods for calculating C1s core-electron binding energies (CEBEs), comparing three functionals—PW86x-PW91c (DFTpw), mPW1PW, and PBE50—across 68 C1s cases in small hydrocarbons and halogenated molecules (alkyl halides), using the delta self-consistent field ΔSCF (or ΔDFT) method developed by one of the authors over the past decade. The PW86x-PW91c functional achieves a root mean square deviation (RMSD) of 0.1735 eV, with improved accuracy for polar C-X bonds (X=O, F) using mPW1PW and PBE50, reducing the average absolute deviation (AAD) to ~0.132 eV. The study emphasizes the role of Hartree–Fock (HF) exchange in refining CEBE predictions and highlights the synergy between theoretical and experimental approaches. These insights lay the groundwork for machine learning (ML)-driven spectral analysis, advancing materials characterization, and catalysis through more reliable automated XPS assignments. Full article

The cocrystallization of trans-[PtI₂(NCR)₂] (R = NMe₂1, NEt₂2, Ph 3, o-ClC₆H₄4) with iodine and iodoform gave the crystalline adducts 1∙4I₂, 2∙2CHI₃, 3∙2CHI₃, and 4∙4I₂, whose structures were studied by single-crystal X-ray diffractometry (XRD). In the structures, apart from the rather predictable C–H⋯I hydrogen bonds (HBs) and I–I⋯I or C–I⋯I halogen bonds (XBs) with the iodide ligands, we identified bifurcated I–I⋯(I–Pt) and C–I⋯(I–Pt) metal-involving XBs, where the platinum center and iodide ligands function as simultaneous XB acceptors toward σ-holes of I atoms in I₂ or CHI₃. Appropriate density functional theory (DFT) calculations (PBE-D3/jorge-DZP-DKH with plane waves in the GAPW method) performed with periodic boundary conditions confirmed the existence of the bifurcated metal-involving I–I⋯(I–Pt) and C–I⋯(I–Pt) interactions and their noncovalent nature. Full article

Microplastics can transfer antibiotics in water through adsorption and desorption, causing adverse effects on the water environment. Therefore, understanding the interaction between microplastics and antibiotics is important in order to assess their impact on the environment. In this study, the adsorption–desorption behaviors of two commonly used antibiotics [enrofloxacin (ENR) and trimethoprim (TMP)] in aquaculture and their interactions with three typical microplastics [polystyrene (PS), polyvinyl chloride (PVC), and polyethylene (PE)] were investigated through laboratory experiments. The results showed that the adsorption capacity of the three microplastics was 1.229–1.698 mg/g for ENR and 1.110–1.306 mg/g for TMP, correlating with the octanol–water partition coefficients ($\log {\mathrm{K}}_{ow}$) of antibiotics. Due to the larger specific surface areas and special functional groups of microplastics, the antibiotic adsorption capacity of PS and PVC was higher than that of PE. The adsorption behavior followed pseudo-second-order kinetics and a Freundlich isotherm model, indicating a non-uniform surface with multilayer adsorption. A thermodynamic analysis showed that these were all spontaneous endothermic adsorptions. X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) analyses indicated that the adsorption mechanism was dominated by physical adsorption, involving π–π conjugation, halogen bonds, hydrogen bonding, and electrostatic interactions. High salinity and alkaline environments were conducive to desorption, and the ENR and TMP desorption rates of the microplastics ranged from 20.65% to 24.95%. This indicates that microplastics adsorbed with antibiotics will desorb antibiotics when entering the seawater system, thereby affecting marine ecosystems. These findings reveal the interaction mechanism between microplastics and aquaculture antibiotics in aqueous systems, providing theoretical support for environmental protection and sustainable development. Full article

A study of the solid-state intermolecular interactions of twenty-nine benzopyrans substituted with polyhaloalkyl groups was carried out by quantum chemical calculations using the Mercury and WinGX computer programs. Molecular structures were obtained from crystallographic information files (CIF) of the CCDC database. C-H—O, C-H—X, C-X—O and C-X—X type contacts, characterized as unconventional hydrogen bonds, were identified and calculated. The criteria used for distances and angles were d(D—A) < R(D) + R(A) + 0.50 and d(H—A) < R(H) + R(A)—0.12°, where D-H—A > 100.0°. D is the donor atom, A is the acceptor atom, R is the Van der Waals radius and d is the interatomic distance. In addition, Etter’s notation was used to describe sets of hydrogen bonds in organic crystals, detailing the intermolecular contacts and periodic arrangements of the crystal packing. It was corroborated that certain positions of halogen atoms and their interactions play an important role in stabilizing the crystal lattice. Full article

In this study, the molecular and crystal structures of iodocymantrenes [Mn(C₅I_nH_5−n)(CO)₂(PPh₃)] (1b n = 1; 2, n = 2; 3, n = 3) are reported and compared with the known structures of [Mn(C₅I_nH_5−n)(CO)₃] (1a, n = 1; 5, n = 5) and [Mn(C₅I₄H)(CO)₂(PPh₃)] (4). In the crystals, many weak interactions like H bonds (H…O, H…I, H…π), halogen bonds (I…I, I…O, I…C, I…π), and π-π contacts are found. Hirshfeld analyses show that H bonding is far more important when the PPh₃ ligand is present, and this is mainly based on dispersive interactions. However, without the PPh₃ ligand, H…I and other I…X contacts are the most frequently observed intermolecular interactions. Full article

To investigate the halogen substitution effect on the anionic spin crossover (SCO) complexes, azobisphenolate ligands with 5,5′-dihalogen substituents from fluorine to iodine were synthesized, and their anionic Fe^III complexes 1F, 1Cl, 1Br, and 1I were isolated. The temperature dependence of magnetic susceptibility and crystal structure revealed that 1F, 1Cl, and 1Br are all isostructural and exhibit SCO with the rotational motion of the cation and ligands, whereas 1I shows incomplete SCO. Note that 1Cl and 1Br showed irreversible and reversible cooperative SCO transitions, respectively. Short intermolecular contacts between the Fe^III complex anions were found despite Coulomb repulsions for all the complexes. The topological analysis of the electron density distributions revealed the existence of X···X halogen bonds, C–H···X, C–H···N, and C–H···O hydrogen bonds, and C–H···π interactions are evident. The dimensionality of intermolecular interactions is suggested to be responsible for the cooperative SCO transitions in 1Cl and 1Br, whereas the disorder due to the freezing of ligand rotations in 1Cl is revealed to inhibit the SCO cooperativity. Full article

The intriguing characteristics of nanoparticles have fueled recent advancement in the field of nanotechnology. In the current study, a microbial-based bioflocculant made from the SCOBY of Kombucha tea broth was purified, profiled, and utilized to biosynthesize iron nanoparticles as a capping and reducing agent. UV–visible absorption spectroscopy, transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), and TGA were used to characterize the Fe nanoparticles. The FT-IR spectra showed functional groups such as hydroxyl, a halogen (C-Br), and carbonyl, and the alkane (C-H) functional groups were present in both samples (bioflocculant and FeNPs) with the exception of the Fe-O bond, which represented the successful biosynthesis of FeNPs. The TEM investigation revealed that the sizes of the produced iron nanoparticles were between 2.6 and 6.2 nm. The UV-vis spectra revealed peaks at 230 nm for the bioflocculant and for the as-fabricated FeNPs, peaks were around 210, 265, and 330 nm, which confirms the formation of FeNPs. X-ray diffraction presented planes (012), (104), (110), (113), (024), (116), and (533) and these planes correspond to 17.17, 32.58, 33.75, 38.18, 45.31, 57.40, and 72.4° at 2Ө. The presence of Fe nanoparticles presented with 0.82 wt% from the EDX spectrum of the biosynthesized FeNPs. However, Fe content was not present from the bioflocculant. SEM images reported cumulus-like particles of the bioflocculant, while that of FeNPs were agglomerated and hexagonal with sizes between 18 and 50 nm. The TGA of FeNPs showed thermal stability by retaining above 60% of its weight at high temperatures. It can therefore be deduced that the purified bioflocculant produced by a yeast Pichia kudraivzevii can be utilized to synthesize FeNPs with the current simple and effective method. Full article

The cis- and trans-isomers of 6-(3-(3,4-dichlorophenyl)-1,2,4-oxadiazol-5-yl)cyclohex-3-ene-1-carboxylic acid (cis-A and trans-A) were obtained by the reaction of 3,4-dichloro-N′-hydroxybenzimidamide and cis-1,2,3,6-tetrahydrophthalic anhydride. Cocrystals of cis-A with appropriate solvents (cis-A‧½(1,2-DCE), cis-A‧½(1,2-DBE), and cis-A‧½C₆H₁₄) were grown from 1,2-dichloroethane (1,2-DCE), 1,2-dibromoethane (1,2-DBE), and a n-hexane/CHCl₃ mixture and then characterized by X-ray crystallography. In their structures, cis-A is self-assembled to give a hybrid 2D supramolecular organic framework (SOF) formed by the cooperative action of O–H⋯O hydrogen bonding, Cl⋯O halogen bonding, and π⋯π stacking. The self-assembled cis-A divides the space between the 2D SOF layers into infinite hollow tunnels incorporating solvent molecules. The energy contribution of each noncovalent interaction to the occurrence of the 2D SOF was verified by several theoretical approaches, including MEP and combined QTAIM and NCIplot analyses. The consideration of the theoretical data proved that hydrogen bonding (approx. −15.2 kcal/mol) is the most important interaction, followed by π⋯π stacking (approx. −11.1 kcal/mol); meanwhile, the contribution of halogen bonding (approx. −3.6 kcal/mol) is the smallest among these interactions. The structure of the isomeric compound trans-A does not exhibit a 2D SOF architecture. It is assembled by the combined action of hydrogen bonding and π⋯π stacking, without the involvement of halogen bonds. A comparison of the cis-A structures with that of trans-A indicated that halogen bonding, although it has the lowest energy in cis-A-based cocrystals, plays a significant role in the crystal design of the hybrid 2D SOF. The majority of the reported porous halogen-bonded organic frameworks were assembled via iodine and bromine-based contacts, while chlorine-based systems—which, in our case, are structure-directing—were unknown before this study. Full article

The removal of decabromodiphenyl ether (BDE 209), as a typical persistent organic pollutant (POP), is of worldwide concern. Mechanochemical (MC) processes are promising methods to degrade environmental pollutants, most of which use a single grinding reagent. The performance of MC processes with co-milling agents still needs to be further verified. In this study, an efficient MC treatment with combined utilization of lithium cobalt oxide (LiCoO₂) and iron (Fe) as co-milling reagents for BDE 209 degradation was investigated. The synchronous action of LiCoO₂ and Fe with a LiCoO₂/Fe/Br molar ratio of 1.5:1.67:1 and a ball-to-powder ratio of 100:1 led to almost thorough-paced abatement and debromination of BDE 209 within 180 min using a ball milling rotation speed of 600 rpm. The reduction in particle sizes and the destruction of crystal structure in mixture powders with the increase in milling time induced the enhanced degradation of BDE 209, as characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The X-ray photoelectron spectroscopy (XPS) characterization showed that the valence state of Co was converted from Co(III) to Co(II), and Fe(0) was changed to Fe(III) when treated with an MC process. This indicated that the reductive debromination of BDE 209 by Fe and the following oxidative degradation of debrominated products by LiCoO₂ were integrated in a concerted way. It proved the removal of BDE 209 via an MC treatment. The full breakage of C-Br and C-O bonds in BDE 209 was confirmed by Fourier transform-infrared spectrometry (FT-IR) spectra, and a possible abatement pathway was also proposed based on the identified intermediate products using gas chromatography–mass spectrometry (GC-MS). These obtained results indicated that a combination of LiCoO₂ and Fe as co-milling reagents is promising in the MC treatment of toxic halogenated pollutants like BDE 209. Full article

The relationship between the strength of a halogen bond (XB) and various IR and NMR spectroscopic quantities is assessed through DFT calculations. Three different Lewis acids place a Br or I atom on a phenyl ring; each is paired with a collection of N and O bases of varying electron donor power. The weakest of the XBs display a C–X bond contraction coupled with a blue shift in the associated frequency, whereas the reverse trends occur for the stronger bonds. The best correlations with the XB interaction energy are observed with the NMR shielding of the C atom directly bonded to X and the coupling constants involving the C–X bond and the C–H/F bond that lies ortho to the X substituent, but these correlations are not accurate enough for the quantitative assessment of energy. These correlations tend to improve as the Lewis acid becomes more potent, which makes for a wider range of XB strengths. Full article

Charge-shift (CS) bonding is a new bonding paradigm in the field of chemical bonds. Our recent study has revealed that certain Cu/Ag/Au-bonds display both CS bonding and ω-bonding characters. In this investigation, we extend our study to halogen bonding. Our focus is on scrutinizing the CS bonding in halogen-bonded BXY (B is a small Lewis base H₂O or NH₃; X and Y are halogen atoms) complexes by using natural bond orbital (NBO) analysis, natural resonance theory (NRT), and atoms in molecules (AIM) methods. The primary objective is to establish a connection between halogen bonding (B–X) in BXY and CS bonding in free XY (di-halogens). The calculations indicate that the studied BXY can be classified into two types. One type with a weak halogen bond shows closed-shell interaction. The other type with a stronger B–X interaction exhibits both CS bonding and ω-bonding characters (as seen in NH₃ClF, NH₃BrF, and NH₃IF). Another interesting finding is a novel propensity that the CS bonding in free XY tends to carry over the halogen bonding in BXY, and the same propensity is found in Cu/Ag/Au ω-bonded species. The present study may offer an approach to probe CS bonding in many more 3c/4e ω-bonded molecules. Full article

Sulphonamides have been one of the major pharmaceutical compound classes since their introduction in the 1930s. Co-crystallisation of sulphonamides with halogen bonding (XB) might lead to a new class of pharmaceutical-relevant co-crystals. We present the synthesis and structural analysis of seven new co-crystals of simple sulphonamides N-methylbenzenesulphonamide (NMBSA), N-phenylmethanesulphonamide (NPMSA), and N-phenylbenzenesulphonamide (BSA), as well as of an anti-diabetic agent Chlorpropamide (CPA), with the model XB-donors 1,4-diiodotetrafluorobenzene (14DITFB), 1,4-dibromotetrafluorobenzene (14DBTFB), and 1,2-diiodotetrafluorobenzene (12DITFB). In the reported co-crystals, X···O/N bonds do not represent the most common intermolecular interaction. Against our rational design expectations and the results of our statistical CSD analysis, the normally less often present X···π interaction dominates the crystal packing. Furthermore, the general interaction pattern in model sulphonamides and the CPA multicomponent crystals differ, mainly due to strong hydrogen bonds blocking possible interaction sites. Full article

In this paper, the synthesis and crystal structure of pyrazine-2,5-diyldimethanol (pyzdmH2, C₆H₈N₂O₂), a new symmetric water-soluble N,O-chelating tetra-dentate organic ligand, is reported and an environmentally friendly method is used to synthesize coordination compounds in water under ambient conditions, from the reaction of pyzdmH2 with the halide salts of Cu(II), Zn(II), Hg(II) and Cd(II): {[Cu(pyzdmH2)_0.5(µ-Br)(Br)(H₂O)]·H₂O}_n 1, {[Zn₂(pyzdmH2)(µ-Cl)(Cl)₃(H₂O)]·H₂O}_n 2, [Hg₂(pyzdmH2)_0.5(µ-Cl)₂(Cl)₂]_n 3, {[Cd₂(pyzdmH2)(µ-Cl)₄]·H₂O}_n 4, and {[Cd₂(pyzdmH2)(µ-Br)₄]·H₂O}_n 5. Single-crystal X-ray diffraction analysis reveals that 1–3 are 1D coordination polymers and 4 and 5 are 3D coordination networks, all constructed by bridging pyrazine-2,5-diyldimethanol and halogen ions. The hydroxyl groups in the organic linker extend the 1D chains to non-covalent 3D networks. In all non-covalent and covalent 3D networks, water molecules are trapped by strong hydrogen bond interactions. Supramolecular analysis reveals strong O-H···O, O-H···N, O-H···X, and weak C-H···O, C-H···X (X = Cl, Br) hydrogen bonds, as well as π-π(pyrazine ring), metal-halogen···π(pyrazine ring), and O-H···ring(5-membered chelate ring) interactions. In addition, X···O weak halogen bonds are present in 1–5 (X = Cl and Br). Full article

Single crystals of a new organic–inorganic hybrid compound (C₃H₇N₆)₂[ZnCl₄]·H₂O was synthesized and characterized by X-ray diffraction at room temperature, FT-IR and FT-Raman spectroscopies, optical absorption and photoluminescence behavior. The title compound belongs to the triclinic space group P$\overline{1},$ and in the crystal structure, the inorganic layers are built from tetrachloridozincate anions [ZnCl₄]²⁻ and free water molecules, linked together by O–H···Cl hydrogen bonds and halogen···halogen interactions. In addition, Hirshfeld surfaces and 2D fingerprint plots estimate the weak intermolecular interactions accountable for the generation of crystal packing. The optimized geometry, vibrational frequencies and various thermodynamic parameters of the title compound calculated using density functional theory (DFT) methods are in agreement with the experimental values. The theoretical calculations were performed using the DFT method at WB97XD/Lanl2dz basis set levels and we discussed topological analysis of atoms in molecules (AIM) at the BCP point. A detailed interpretation of the IR and Raman spectra were reported. Additionally, the simulated spectrum satisfactorily coincided with the experimental UV-Visible spectrum. A wide band gap exceeding 4 eV of the synthesized compound was recorded. The photoluminescence (PL) was characterized through two bands successively at 453 and 477 nm. Ultimately, antimicrobial activity and enzymatic inhibition assays of the complex were also investigated through microbial strains, agar diffusion method, minimum inhibitory concentration (MIC) determination, lipase and phospholipase A₂ inhibition. Full article

Four Ni–phen complexes were prepared and characterized by FTIR and thermal analysis. The X-ray structure determination shows that the geometry around Ni^II ions in complexes 1, [Ni(phen)₂(H₂O)(ONO₂)](NO₃); 2, [Ni(phen)₂(H₂O)Cl]Cl; 3, [Ni(phen)(CH₃CN)(ONO₂)(O₂NO)] and 4, [Ni(phen)₃](NO₃)₂.H₂O.C₂H₅OH is considerably distorted octahedral. The coordination core geometries in 1, 2, 3 and 4 are NiN₄O₂, NiN₄OCl, NiN₃O₃ and NiN₆, respectively. The crystal packing and crystal supramolecularity analysis of the complexes reveal the importance of aryl∙∙∙aryl interactions, and both offset face-to-face (OFF) and edge-to-face (EF) motifs are dominant. Hydrogen bonding interactions in these structures reinforce aryl∙∙∙aryl interactions. FTIR proved the coordination of M-N and M-Cl as well as the presence of nitro groups in the complexes, while thermal analysis revealed that the loss of water, chloro and nitro groups occurred before the degradation of phenanthroline ligand in the complexes. DFT study indicates that a strong correlation exists among theoretical and experimentally determined geometric parameters with distorted octahedral geometry. The charge density in HOMO is localized on the metal halogen bond and nitrate group (NO₃⁻), whereas the LUMO cloud density is mainly distributed on the phen ring, which indicates the electroactive nature of the ring. Full article