Crystal Structure Determination Research Articles

Binder-Mediated Supramolecular Polymerization with Controllable Gel-to-Crystal Transformation in Metal-Organic Polyhedra.

Controlling supramolecular polymerization across various length scales through metal-organic polyhedra in aqueous media enables functional nanomaterial fabrication beyond traditional π-chromophoric systems. Herein, we present a straightforward strategy to tune the nano- and microscopic structural evolution of a co-assembled system. Ga-MOC ([Ga8(ImDC)12]12-, ImDC = imidazoledicarboxylate) is introduced as a discrete unit, while the Ni-ethylenediamine complex [Ni(en)3]2+ (Ni-en), served as the binder towards supramolecular polymerization. Comprehensive investigations revealed that adjusting the binder ratio in the bicomponent (Ga-MOC and Ni-en) co-assembly process allows precise control over nanostructure length and evolution by influencing both the kinetics and thermodynamics of the assembly. At higher concentrations, this assembly forms a hydrogel above a critical binder ratio. Furthermore, the binder's ratio significantly influences the viscoelastic strength of the hydrogels by modulating the connectivity between the MOCs through hydrogen (H)-bonding. Intriguingly, the hydrogels gradually transformed into crystals without any external stimuli, with different timescales regulated by the binder ratio. Single crystal structure determination reveals a 3D structure composed of Ga-MOC and Ni-en, extended through charge-assisted H-bonding (CAHB) interactions, resulting through the transformation from a kinetically controlled gel state to a thermodynamically stable crystal product. This study provides an understanding of binder-mediated control over nanostructural evolution in co-assembled MOCs.

Strontioborite: revalidation as a mineral species and new data

Abstract Strontioborite, which was first described in 1960 and later discredited by the then named Commission on New Minerals and Mineral Names of the International Mineralogical Association (IMA CNMMN), has been re-investigated (electron microprobe, single-crystal and powder X-ray diffraction, crystal structure determination and IR spectroscopy) on two specimens, including the holotype, and revalidated by the IMA Commission on New Minerals, Nomenclature and Classification (CNMNC). Strontioborite is known only at the Chelkar salt dome (North Caspian Region, Western Kazakhstan), in halite rocks with bischofite, magnesite, anhydrite, halurgite, boracite, ginorite and celestine. It forms colourless lamellar, scaly or tabular crystals up to 2 mm across. The chemical composition (wt.%, H2O is calculated for (OH)4 = 4 H apfu, according to structural data; holotype/neotype) is: CaO 1.42/0.27, SrO 23.10/23.79, B2O3 67.37/67.57, H2O 8.73/8.72, total 100.62/100.37. The empirical formulae [calculated based on 15 O apfu = O11(OH)4 pfu] of the holotype and neotype specimens are Sr0.92Ca0.10B7.98O11(OH)4 and Sr0.95Ca0.02B8.02O11(OH)4, respectively. The idealised formula is Sr[B8O11(OH)4]. Strontioborite is monoclinic, space group P21, a = 7.6192(3), b = 8.1867(2), c = 9.9164(3) Å, β = 108.357(4)°, V = 587.07(3) Å3 and Z = 2. The strongest reflections of the powder X-ray diffraction pattern [d,Å(I)(hkl)] are: 7.22(100)(100), 5.409(61)(110), 4.090(64)(020), 3.300(48)(210), 2.121(30)( $\bar{1}$ 24) and 2.043(37)(040, 024, $\bar{2}$ 24). The crystal structure, solved from single-crystal X-ray diffraction data (R = 0.0372), is based upon the (100) layers of polymerised B–O–OH polyanions [B8O11(OH)4]2– and Sr-centred nine-fold polyhedra SrO6(OH)3. The B–O–OH polyanion is the cluster of three tetrahedra and three triangles; these clusters are decorated by the [B2O2(OH)3] pyro-group consisting of two triangles. The layers are linked via vertices of Sr-centred polyhedra, which share seven vertices with B-centred polyhedra of one layer and two vertices with B-centred polyhedra of the adjacent layer, and by the system of H bonds. The crystal chemistry of strontioborite is discussed in comparison with other natural and synthetic borates.

Expression, characterization and application of the deoxynivalenol dehydrogenase from Devosia yakushimensis.

Deoxynivalenol (DON) is one of the type-B trichothecene mycotoxins generally produced by Fusarium fungi and widely pollutes wheat and other grains, causing a great loss in grain yield and significant threat to human health. Enzymatic treatment of DON has displayed a significant role in controlling its levels in recent years. Here, the DON dehydrogenase from Devosia yakushimensis (DeDDH) is reported. DeDDH exhibited the highest activity in an environment of 35 °C and pH 7.5. In addition, the residual activity of DeDDH was about 40% after pre-incubation at 80 °C for 0.5 h, suggesting a good thermostability. The presence of Ca2+ significantly boosted the activity of DeDDH, but substituting Ca2+ with other ions could hardly retain the activity. At the optimal conditions, DeDDH efficiently degraded 75% DON (45 μg mL-1) within 4 h. Notably, when three cofactors, PQQ, PMS and DCPIP, were added together, more than 90% DON (45 μg mL-1) was quickly degraded in the first 40 min. The residues Thr485 and Leu521 were found to be significant to the activity of DeDDH by site-directed mutagenesis, much different from other DON dehydrogenases. Nevertheless, further research on the crystal structure determination of DeDDH, key catalytic residue identification, catalytic activity and thermostability modification still needs to be conducted for application in industry. © 2024 Society of Chemical Industry.

The coordination chemistry and anticancer activity of organo-ruthenium(II), -iridium(III) and -rhodium(III) complexes with sulfonyl-substituted thiourea ligands.

Some half-sandwich compounds with a variety of ligands and metal centres have shown promising anticancer activity. Herein we report a series of reactions between the sulfonylthiourea ligands p-TolSO2NHC(S)NHPh, EtSO2NHC(S)NHPh and CH3SO2NHC(S)NHPh and [(η6-p-cymene)RuCl2]2, [(η6-arene)RuCl2(PR3)] (arene = benzene or p-cymene), [Cp*MCl2(PR3)] or [Cp*RhCl2]2 (M = Ir(III), Rh(III)), Cp* = η5-pentamethylcyclopentadienyl, PR3 = triphenylphosphine (PPh3), tris(2-cyanoethyl)phosphine (tcep) and 1,3,5-triaza-7-phosphaadamantane (pta) and their corresponding piano stool complexes. Single crystal X-ray diffraction structure determinations indicated that the resulting linkage isomer of the complex, i.e., proximal (coordination via S,N(sulfonated) placing the sulfonyl group near the coordination sphere) or distal (coordination via S,N(non-sulfonated), placing the sulfonyl group away from the coordination sphere), is directly related to the steric bulk around the metal centre. Proximal to distal isomerisation of the complex [(η6-p-cymene)Ru{p-TolSO2NC(S)N(PPh3)}] (1aL1) was observed by 1H and 31P{1H} NMR spectroscopy. DFT calculations suggested this to be the result of the conversion from the initially formed kinetically favourable to the thermodynamically favourable isomer. Computational investigation of non-covalent interactions using the reduced density gradient also revealed a chalcogen bond present between the thiourea sulfur and sulfonyl oxygen atoms of complex 1aLa. The in vitro antiproliferative activity of several complexes was determined against human cancer cells, which revealed a correlation between potency and lipophilic properties of the ancillary ligands for a series of Ru(II) p-cymene complexes.

Visualizing supramolecular assembly behavior, stimulus response, and solid state emission of higher-order Pt2+ aggregates.

Here, we present the first instance of a highly efficient red tetramer aggregate with tunable emission based on a cationic platinum(II) complex in conjunction with a silver cluster anion counterpart. This system exhibits multicolor emission response behaviors, which can be conveniently and directly detected through spectroscopic analysis, showcasing intriguing luminescence changes. The self-assembly of Pt⋯, π-π, and hydrogen bonding interactions not only enables an intriguing color adjustment from green to yellow emission, and eventually to red emission, but also demonstrates the co-existence of the monomer, excimer, and aggregation. These phenomena are further accompanied by well-defined nanostructures. The self-assembly process of these structures exhibits an isodesmic growth mechanism, which is dependent on temperature. In this regard, it exhibits potential applicability in multi-mode logic gates that rely on external stimuli such as concentration, solvent, and temperature. The sensitivity of the aggregates towards chemical stimuli combined with their exceptionally bright emission characteristics renders them suitable for diverse applications including solid-state lighting sensing mechanisms and anticounterfeiting measures. The multi-stimuli responsive phosphorescence and self-assembly behaviors of the cationic platinum(II) complex were substantiated by X-ray crystal structure determination, 1H NMR analysis spectroscopic investigations, computational calculations and scanning electron microscopy (SEM) studies.

Utilizing MEDT analysis of [3 + 2] cycloaddition reaction: x-ray crystallography of spirooxindole linked with thiophene/furan heterocycles and triazole framework

Hybridization of spirooxindole with different pharmacophores such as triazole and heterocycle such as thiophene and furan moiety was achieved by the [3 + 2] cycloaddition (32CA) reaction approach. Structural investigations of the compounds 4a and 4b were performed using X-ray single crystal structure determinations and Hirshfeld analysis. Both compounds crystallized in monoclinic crystal system. The space group is P21/c for 4a and P21/n for 4b. The crystal parameters are a = 10.2619(3) Å, b = 13.6776(3) Å, c = 10.9318(3), β = 116.640(4)° for the former while a = 13.0012(1) Å, b = 14.9692(1) Å, c = 14.1178(1) Å, β = 97.101(1)° for the latter. In both compounds, the aryl group and the triazole moieties are twisted from one another. The twist angle is 84.75˚for 4a while 86.64˚ for 4b. Based on Hirshfeld calculations, the Cl…H, O…H, N…H and C…H non-covalent interactions in 4a while the O…H interactions in 4b are the most important. The molecular mechanism of the key 32CA reaction between the in situ generated azomethine ylides and the corresponding chalcones has been studied within the Molecular Electron Density Theory (MEDT). The MEDT study reveals that the low activation energies and high experimental selectivity are the result of the supernucleophilic character of the ylides and the strong electrophilicity of the chalcones, which favour the process through a high polar character. This high polar character accounts for the total endo selectivity experimentally found.

Synthesis, Structure and Catalytic Properties of Hyp3[Ge9Rh]PPh3

In single‐site homogeneous catalysts (SSHoCs) transition metal atoms are incorporated in the surface of a small homoatomic atom cluster. Within this concept the main group element cluster is considered as innocent support material, while the catalysis itself is realised at the transition metal atom. In the case of [Ge9] clusters, both transition metal atoms and the Ge atoms have low oxidation state. Thus improving the synthesis towards transition metal decorated Zintl cluster has become important in the last years, and the catalytic activity of these clusters is of high interest. An optimised one‐step synthetic protocol for Hyp3[Ge9Rh]PPh3 is presented. The product is characterised by NMR spectroscopy, LIFDI/MS and single crystal structure determination. The Rh atom is incorporated in the clusters surface and bridges a deltahedral cluster face, whereby one of the triangular edge opens forming an almost planar face of three Ge and one Rh atom. PPh3 ligand dissociation as well as the catalytic activity in the isomerisation of 1‐hexene and allylbenzene as well as the hydrogenation of those substrates with hydrogen is investigated.

Cold and Liquid Crystal Properties of Square-Planar Copper(II) Versus Nickel(II)- Iminophenolate/Naphthalen-2-Olate Schiff Base Complexes.

Reaction of the phenolate or naphthalen-2-olate based Schiff base ligands, (E)-1-((2-ethylphenylimino)methyl)phenol (HL1) or (E)-1-((2-ethylphenylimino)methyl)naphthalen-2-ol (HL2) with nickel(II) and copper(II) acetate provides the complexes bis[(E)-1-((2-ethylphenylimino)methyl)phenolato-ĸ2N,O]Ni/Cu(II), [Ni(L1)2] (1) and [Cu(L1)2] (2), or bis[(E)-1-((2-ethylphenylimino)methyl)naphthalen-2-olato-ĸ2N,O]Ni/Cu(II), [Ni(L2)2] (3) and [Cu(L2)2] (4), respectively. Single crystal X-ray structure determinations for 1, 3 and 4 reveal N2,O2-metal coordination of two chelating Schiff base ligands in a square-planar geometry. Powder X-ray diffractograms confirm the phase purity of the bulk microcrystalline samples. Thermal analyses by differential scanning calorimetry (DSC) and polarized light microscopic (PLM) indicate the copper(II) complexes to exhibit cold crystal (2) and liquid crystal (4) property. Cyclic voltammograms suggest an irreversible electrochemical process with two one electron charge transfer processes in N,N-dimethylformamide. Variable temperature magnetic measurements at the solid-state prove the diamagnetic nature of the low-spin Ni2+ centres in 1 or 3, as expected from the square-planar coordination geometry with rather strong ligands. The complexes expose medium level of antioxidant activity in methanol. Optimized geometry and excited state property by DFT/TD-DFT correspond well to the experimental results of the electronic and molecular structure at the ground state.

On the humanization of VHHs: Prospective case studies, experimental and computational characterization of structural determinants for functionality.

The humanization of camelid-derived variable domain heavy chain antibodies (VHHs) poses challenges including immunogenicity, stability, and potential reduction of affinity. Critical to this process are complementarity-determining regions (CDRs), Vernier and Hallmark residues, shaping the three-dimensional fold and influencing VHH structure and function. Additionally, the presence of non-canonical disulfide bonds further contributes to conformational stability and antigen binding. In this study, we systematically humanized two camelid-derived VHHs targeting the natural cytotoxicity receptor NKp30. Key structural positions in Vernier and Hallmark regions were exchanged with residues from the most similar human germline sequences. The resulting variants were characterized for binding affinities, yield, and purity. Structural binding modes were elucidated through crystal structure determination and AlphaFold2 predictions, providing insights into differences in binding affinity. Comparative structural and molecular dynamics characterizations of selected variants were performed to rationalize their functional properties and elucidate the role of specific sequence motifs in antigen binding. Furthermore, systematic analyses of next-generation sequencing (NGS) and Protein Data Bank (PDB) data was conducted, shedding light on the functional significance of Hallmark motifs and non-canonical disulfide bonds in VHHs in general. Overall, this study provides valuable insights into the structural determinants governing the functional properties of VHHs, offering a roadmap for their rational design, humanization, and optimization for therapeutic applications.

Synthesis, Characterization, Crystal structure determination and DFT study of a six coordinated Cu (II) complex of a phosphorous based tris-(2-pyridinylamino) phosphene sulphide ligand and its acid catalysed hydrolysis

One mono nuclear copper(II) complex (Cu-TPPS-OOCCH3 with structural formula C17H19CuN6O3PS) is synthesized using a novel tripodal tetradentate ligand, tris-(2-pyridinylamino)phosphene sulphide (TPPS), which has three pyridinylamino groups attached to a phosphorus atom connected to a sulphur atom (PS). The equatorial positions of the complex are occupied by three amino N-atoms of three aminopyridyl groups and one O-atom of the acetate group. The apical position is occupied by other O-atom of acetate group and one secondary N-atom of the tripodal ligand. The complex has been synthesized and purified as green solid and characterized by various spectroscopic techniques and the structure has been determined by X-ray single crystal diffraction study. The geometry optimizations and calculations of energies of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the compounds are performed by using the hybrid B3LYP density functional theory (DFT) along with the def2TZVP basis set.

Influence of Peripheral Substituents on Fe(II) Spin State in Complexes with Tridentate Schiff‐Base Ligands

AbstractSix Fe(II) complexes with substituted 6‐((quinoline‐8‐ylimino)methyl)phenolates (R2qsal) were synthesized. X‐ray crystal structure determination for [Fe(R2qsal)2], where R=F (1), Cl (2), Br (3), I (4), CF3/H (5), or CN/H (6), revealed mononuclear complexes that crystallize either solvent‐free in case of 1, 5, and 6 or as CH2Cl2 solvates in the case of 2, 3, and 4. Complexes 1–4, which contain π‐donating substituents, exhibit only high‐spin (HS) state, as shown by crystal structure analysis and magnetic measurements. In contrast, complexes 5 and 6, which contain electron‐withdrawing substituents, exist in the low‐spin (LS) state at lower temperatures but exhibit crossover to the HS state above 300 K. Electronic structure calculations show a good correlation between the relative energies of the LS and HS states and the experimentally observed behavior.

Kinetic and catalytic mechanism of the methionine-derived glucosinolate biosynthesis enzyme methylthioalkylmalate synthase

In Brassica plants, methionine-derived aliphatic glucosinolates are chemically diverse natural products that serve as plant defense compounds, as well as molecules with dietary health-promoting effects. During their biosynthesis, methylthioalkylmalate synthase (MAMS) catalyzes the elongation reaction of the aliphatic chain. The MAMS-catalyzed condensation of 4-methylthio-2-oxobutanoic acid and acetyl-CoA generates a 2-malate derivative that either enters the pathway for the synthesis of C3-glucosinolates or undergoes additional extension reactions, which lead to C4- to C9-glucosinolates. Recent determination of the x-ray crystal structure of MAMS from Brassica juncea (Indian mustard) provided insight on the molecular evolution of MAMS, especially substrate specificity changes, from the leucine biosynthesis enzyme α-isopropylmalate synthase but left details of the reaction mechanism unanswered. Here we use the B.juncea MAMS2A (BjMAMS2A) isoform to analyze the kinetic and catalytic mechanisms of this enzyme. Initial velocity studies indicate that MAMS follows an ordered bi bi kinetic mechanism, which based on the x-ray crystal structure, involves binding of 4-methylthio-2-oxobutanoic acid followed by acetyl-CoA. Examination of the pH-dependence of kcat and kcat/Km are consistent with acid/base catalysis. Site-directed mutagenesis of three residues originally proposed to function in the reaction mechanism-Arg89 (R89A, R89K, R89Q), Glu227 (E227A, E227D, E227Q), and His388 (H388A, H388N, H388Q, H388D, and H388E)-showed that only two mutants (E227Q and H388N) retained activity. Based on available structural and biochemical data, a revised reaction mechanism for MAMS-catalyzed elongation of methionine-derived aliphatic glucosinolates is proposed, which is likely also conserved in α-isopropylmalate synthase from leucine biosynthesis in plants and microbes.

Crystal Structure Determination from Powder Diffraction Patterns with Generative Machine Learning.

Powder X-ray diffraction (PXRD) is a cornerstone technique in materials characterization. However, complete structure determination from PXRD patterns alone remains time-consuming and is often intractable, especially for novel materials. Current machine learning (ML) approaches to PXRD analysis predict only a subset of the total information that comprises a crystal structure. We developed a pioneering generative ML model designed to solve crystal structures from real-world experimental PXRD data. In addition to strong performance on simulated diffraction patterns, we demonstrate full structure solutions over a large set of experimental diffraction patterns. Benchmarking our model, we predicted the structure for 134 experimental patterns from the RRUFF database and thousands of simulated patterns from the Materials Project on which our model achieves state-of-the-art 42 and 67% match rate, respectively. Further, we applied our model to determine the unreported structures of materials such as NaCu2P2, Ca2MnTeO6, ZrGe6Ni6, LuOF, and HoNdV2O8 from the Powder Diffraction File database. We extended this methodology to new materials created in our lab at high pressure with previously unsolved structures and found the new binary compounds Rh3Bi, RuBi2, and KBi3. We expect that our model will open avenues toward materials discovery under conditions which preclude single crystal growth and toward automated materials discovery pipelines, opening the door to new domains of chemistry.

Disulfide Bond Engineering of Soluble ACE2 for Thermal Stability Enhancement.

Although the primary pandemic of SARS-CoV-2 is over, there are concerns about the resurgence of the next wave of related viruses, including a wide range of variant viruses. The soluble ACE2 (sACE2) inhibits the SARS-CoV-2 spike protein ACE2 interaction and has potential as a variant-independent therapeutic against SARS-CoV-2. Here, we introduce novel disulfide bonds in the wild-type sACE2-Fc by structure-guided mutagenesis, aiming to improve its stability. The stability of each mutant was assessed by a thermal shift assay to screen mutants with increased thermal stability. As a result, we identified a mutant sACE2-Fc with a significantly increased melting temperature. X-ray crystal structure determination of the sACE2 mutant confirmed the correct formation of the designed disulfide bond, and there were no significant structural disturbances. We also proved that the thermostable sACE2-Fc preserved the spike protein binding affinity comparable to the wild-type sACE2-Fc in both molecular and cellular environments, suggesting its therapeutic potential.

Structural analysis of a ligand-triggered intermolecular disulfide switch in a major latex protein from opium poppy.

Several proteins from plant pathogenesis-related family 10 (PR10) are highly abundant in the latex of opium poppy and have recently been shown to play diverse and important roles in the biosynthesis of benzylisoquinoline alkaloids (BIAs). The recent determination of the first crystal structures of PR10-10 showed how large conformational changes in a surface loop and adjacent β-strand are coupled to the binding of BIA compounds to the central hydrophobic binding pocket. A more detailed analysis of these conformational changes is now reported to further clarify how ligand binding is coupled to the formation and cleavage of an intermolecular disulfide bond that is only sterically allowed when the BIA binding pocket is empty. To decouple ligand binding from disulfide-bond formation, each of the two highly conserved cysteine residues (Cys59 and Cys155) in PR10-10 was replaced with serine using site-directed mutagenesis. Crystal structures of the Cys59Ser mutant were determined in the presence of papaverine and in the absence of exogenous BIA compounds. A crystal structure of the Cys155Ser mutant was also determined in the absence ofexogenous BIA compounds. All three of these crystal structures reveal conformations similar to that of wild-type PR10-10 with bound BIA compounds. In the absence of exogenous BIA compounds, the Cys59Ser and Cys155Ser mutants appear to bind an unidentified ligand or mixture of ligands that was presumably introduced during expression of the proteins in Escherichia coli. The analysis of conformational changes triggered by the binding of BIA compounds suggests a molecular mechanism coupling ligand binding to the disruption of an intermolecular disulfide bond. This mechanism may be involved in the regulation of biosynthetic reactions in plants and possibly other organisms.

Potential building blocks for porous organic materials

2,4-Difluoronitrobenzene has been reacted with a linker diamine (ethylenediamine or propylenediamine) and butylamine, in either order, to give new molecular building blocks for porous supramolecular networks. Two structures were established by X-ray single crystal structure determinations. The propylenediamine structure displays small pores, which may be due to the longer and more flexible linker in the structure.

Improvement of Single-Crystal Structures of Very Heavy Element Compounds by Refining Anomalous Dispersion Parameters.

Refining the anomalous dispersion parameters of the four uranium compounds NaUF5, NaU2F9, Cs2(UO2)TiO4, and Cs2(UO2)Ti2O6 gave insights into the crystallographic model improvement of very heavy atoms. We found that the values for the dispersive and absorptive parts, f' and f″, closely followed the X-ray absorption spectra on their L3, L2, and L1 edges. The obtained values are sensitive to the chemical environment at each crystallographically independent position. An incorrect treatment of the anomalous dispersion correction can lead to a wrong crystallographic model. The above-mentioned, already published structures were improved by this process. General guidelines were given for the crystal structure determination of very heavy compounds. When using Mo Kα radiation with uranium compounds, the proximity of its energy to the uranium L-edges causes a noticeable effect.

Deciphering the cytotoxic and antioxidant potential of 3,5-disubstituted isoxazole-linked benzimidazolone derivatives

A series of new isoxazole derivatives containing a benzimidazolone has been synthesized by cycloaddition reaction using various nitrile oxides. In all cases, these cycloadditions are completely chemo and regioselective. The structures of the new cycloadducts were characterized by 1H, 13C NMR spectroscopy, HRMS and confirmed in one case by a single crystal structure determination. The isoxazole compounds were evaluated for in vitro antioxidant activity using the DPPH and ABTS methods. As a result, compound 5a showed good antioxidant activity. The results of the acute toxicity study of the heterocycles studied by the oral route showed no deaths and no clinical signs of toxicity. Additionally, the Hirshfeld surface analysis and the molecular electrostatic potential using density functional theory (DFT) modeling at the B3LYP/6–31G(d,p) level. Hirshfeld surface analysis (dnorm surface and 2D-fingerprint plots) revealed the nature of intermolecular contacts. H⋯H interactions make the most significant contribution to crystal packing. The optimized structural parameters obtained through DFT calculations closely matched those determined via X-ray analysis, demonstrating strong agreement between theoretical predictions and experimental observations.

The influence of the pyridyl substituent in N-methyl-P,P-diphenyl-N-2-pyridinyl-phosphinous amide ligand on the coordination chemistry of group 6B metal carbonyl derivatives

The reaction of N-methyl-P,P-diphenyl-N-2-pyridinyl-phosphinous amide (1) with group 6B metal hexa, tetra, and tricarbonyls yielded the same octahedral complexes cis-M(CO)4[1-κ2P,Npy] (M = Cr(2), Mo(3), W(4)) in which the ligand chelates only in a bidentate fashion through its phosphorus atom and pyridyl N-atom. Compounds 1–4 were identified and characterized by multinuclear NMR spectroscopy (1H, 13C, 31P NMR), elemental analysis, IR and UV–Vis spectroscopy. Complexes 2–4 exhibited weak metal-to-ligand charge transfer transitions unaffected by solvent polarity. Crystal structure determination is carried out on complex 4.

Synthesis, characterization, and biological evaluation of novel cobalt(II) complexes with β-diketonates: crystal structure determination, BSA binding properties and molecular docking study.

In order to discover a new antibiotic drug with better or similar activity of the already existing drugs, a series of novel cobalt(II) complexes with β-diketonate as ligands is synthesized and tested on four strains of bacteria and four species of fungi. All compounds showed notable antimicrobial activityagainst all tested strains. More importantly, some cobalt(II) complexes displayed greater activity than ketoconazole. It is important to notice that on the tested strains Mucor mucedo and Penicillium italicum complex 2B showed five times better activity compared to ketoconazole, while complex 2D had two times better activity on Penicillium italicum strain compared to ketoconazole. Moreover, investigations with bovine serum albumin were performed. Investigations showed that the tested complexes have an appropriate affinity for binding to bovine serum albumin. In addition, the molecular docking study was performed to investigate more specifically the sites and binding mode of the tested cobalt(II) complexes with β-diketonate as ligands to bovine serum albumin, tyrosyl-tRNA synthetase, topoisomerase II DNA gyrase, and cytochrome P450 14 alpha-sterol demethylase. In conclusion, all the results indicated the great prospective of the novel cobalt complexes for some potential clinical applications in the future.