Syntheses, characterizations, crystal structures and Hirshfeld surface analyses of methyl 4-[4-(di-fluorometh-oxy)phen-yl]-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexa-hydro-quinoline-3-carboxyl-ate, isopropyl 4-[4-(di-fluoro-meth-oxy)phen-yl]-2,6,6-trimethyl-5-oxo-1,4,5,6,7,8-hexa-hydro-quinoline-3-carboxyl-ate and tert-butyl 4-[4-(di-fluoro-meth-oxy)phen-yl]-2,6,6-trimethyl-5-oxo-1,4,5,6,7,8-hexa-hydro-quinoline-3-carboxyl-ate.

The crystal structures and Hirshfeld surface analyses of three similar compounds are reported. Methyl 4-[4-(di-fluoro-meth-oxy)phen-yl]-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexa-hydro-quinoline-3-carboxyl-ate, (C21H23F2NO4), (I), crystallizes in the monoclinic space group C2/c with Z = 8, while isopropyl 4-[4-(di-fluoro-meth-oxy)phen-yl]-2,6,6-trimethyl-5-oxo-1,4,5,6,7,8-hexa-hydro-quinoline-3-carb-oxyl-ate, (C23H27F2NO4), (II) and tert-butyl 4-[4-(di-fluoro-meth-oxy)phen-yl]-2,6,6-trimethyl-5-oxo-1,4,5,6,7,8-hexa-hydro-quinoline-3-carboxyl-ate, (C24H29F2NO4), (III) crystallize in the ortho-rhom-bic space group Pbca with Z = 8. In the crystal structure of (I), mol-ecules are linked by N-H⋯O and C-H⋯O inter-actions, forming a tri-periodic network, while mol-ecules of (II) and (III) are linked by N-H⋯O, C-H⋯F and C-H⋯π inter-actions, forming layers parallel to (002). The cohesion of the mol-ecular packing is ensured by van der Waals forces between these layers. In (I), the atoms of the 4-di-fluoro-meth-oxy-phenyl group are disordered over two sets of sites in a 0.647 (3): 0.353 (3) ratio. In (III), the atoms of the dimethyl group attached to the cyclo-hexane ring, and the two carbon atoms of the cyclo-hexane ring are disordered over two sets of sites in a 0.646 (3):0.354 (3) ratio.

Synthesis, characterization, and cancer cell-selective cytotoxicity of mixed-ligand cobalt(III) complexes of 8-hydroxyquinolines and phenanthroline bases.

Transition metal complexes exhibiting selective toxicity towards a broad range of cancer types are highly desirable as potential anticancer agents. Herein, we report the synthesis, characterization, and cytotoxicity studies of six new mixed-ligand cobalt(III) complexes of general formula [Co(B)2(L)](ClO4)2 (1-6), where B is a N,N-donor phenanthroline base, namely, 1,10-phenanthroline (phen in 1, 2), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq in 3, 4), and dipyrido[3,2-a:2',3'-c]phenazine (dppz in 5, 6), and L is the monoanion of 8-hydroxyquinoline (HQ in 1, 3, 5) and 5-chloro-7-iodo-8-hydroxyquinoline (CQ in 2, 4, 6). The X-ray single crystal structures of complexes 1 and 2 as PF6- salts revealed a distorted octahedral CoN5O coordination environment. Complexes demonstrated good stability in an aqueous buffer medium and in the presence of ascorbic acid as a reductant. Cytotoxicity studies using a panel of nine cancer cell lines showed that complex 6, with the dppz and CQ ligands, was significantly toxic against most cancer cell types, yielding IC50 values in the range of 2 to 14 µM. Complexes 1, 3, and 5, containing the HQ ligand, displayed lower toxicity compared to their CQ counterparts. The phenanthroline complexes demonstrated marginal toxicity towards the tested cell lines, while the dpq complexes exhibited moderate toxicity. Interestingly, all complexes demonstrated negligible toxicity towards normal HEK-293 kidney cells (IC50 > 100 µM). The observed cytotoxicity of the complexes correlated well with their lipophilicities (dppz > dpq > phen). The cytotoxicity of complex 6 was comparable to that of the clinical drug cisplatin under similar conditions. Notably, neither the HQ nor the CQ ligands alone demonstrated noticeable toxicity against any of the tested cell lines. The Annexin-V-FITC and DCFDA assays revealed that the cell death mechanism induced by the complexes involved apoptosis, which could be attributed to the metal-assisted generation of reactive oxygen species. Overall, the dppz complex 6, with its remarkable cytotoxicity against a broad range of cancer cells and negligible toxicity toward normal cells, holds significant potential for cancer chemotherapeutic applications.

Hydrogen-bonding interactions in 5-fluorocytosine-urea (2/1), 5-fluorocytosine-5-fluorocytosinium 3,5-dinitrosalicylate-water (2/1/1) and 2-amino-4-chloro-6-methylpyrimidine-6-chloronicotinic acid (1/1).

Three new compounds, namely, 5-fluorocytosine-urea (2/1), 2C4H4FN3O·CH4N2O, (I), 5-fluorocytosine-5-fluorocytosinium 3,5-dinitrosalicylate-water (2/1/1), 2C4H4FN3O·C4H5FN3O+·C7H2N2O7-·H2O, (II), and 2-amino-4-chloro-6-methylpyrimidine-6-chloronicotinic acid (1/1), C6H4ClNO2·C5H6ClN3, (III), have been synthesized and characterized by single-crystal X-ray diffraction. In compound (I), 5-fluorocytosine (5FC) molecules A and B form two different homosynthons [R22(8) ring motif], one formed via N-H...O hydrogen bonds and the second via N-H...N hydrogen bonds. In addition to this interaction, a sequence of fused-ring motifs [R21(6), R33(8), R22(8), R43(10) and R22(8)] are formed, generating a supramolecular ladder-like hydrogen-bonded pattern. In compound (II), 5FC and 5-fluorocytosinium are linked by triple hydrogen bonds, generating two fused-ring motifs [R22(8)]. The neutral 5FC and protonated 5-fluorocytosinum cation form a dimeric synthon [R22(8) ring motif] via N-H...O and N-H...N hydrogen bonds. On either side of the dimeric synthon, the neutral 5FC, 5-fluorocytosinium cation, 3,5-dinitrosalicylate anion and water molecule are hydrogen bonded through N-H...O, N-H...N, N-H...OW and OW-HW...O hydrogen bonds, forming a large ring motif [R1010(56)], leading to a three-dimensional supramolecular network. In compound (III), 2-amino-4-chloro-6-methylpyrimidine (ACP) interacts with the carboxylic acid group of 6-chloronicotinic acid via N-H...O and O-H...O hydrogen bonds, generating an R22(8) primary ring motif. Furthermore, the ACP molecules form a base pair via N-H...N hydrogen bonds. The primary motif and base pair combine to form tetrameric units, which are further connected by Cl...Cl interactions. In addition to this hydrogen-bonding interaction, compounds (I) and (III) are further enriched by π-π stacking interactions.

Chemistry of a series of heterobimetallic complexes MnIII2(CaII/SrII)X2 (X = Cl-, Br-).

This manuscript describes the syntheses, structures and magnetism of MnIII-CaII/SrII complexes which are compositionally relevant in the context of the oxygen evolving complex (OEC) of photosystem II (PS II). A series of trimetallic tetraoxo complexes containing redox-inactive metal ions CaII or SrII were synthesized using a tetranucleating ligand framework. The structural characteristics of these complexes, with the oxido ligands bridging the redox-inactive metals and the manganese centres, make them particularly relevant to biological and heterogeneous metal-oxido clusters. Electrochemical studies of these compounds show that the reduction potentials are highly dependent upon the Lewis acidity of the redox-inactive metal, identifying the chemical basis for the observed differences in electrochemistry. This correlation provides insights into the role of the CaII/SrII ion in modulating the redox potential of the OEC and of other redox-inactive ions in tuning the redox potentials of other metal-oxide electrocatalysts. Temperature dependent magnetic measurements have also been performed for the complexes.

Synthesis, crystal structure, Hirshfeld surface analysis, DFT and NBO study of ethyl 1-(4-fluoro-phen-yl)-4-[(4-fluoro-phen-yl)amino]-2,6-diphenyl-1,2,5,6-tetra-hydro-pyridine-3-carboxyl-ate.

The title com-pound, C32H28F2N2O2, a highly functionalized tetra-hydro-pyridine, was synthesized by a one-pot multi-com-ponent reaction of 4-fluoro-aniline, ethyl aceto-acetate and benzaldehyde at room temperature using sodium lauryl sulfate as a catalyst. The com-pound crystallizes with two mol-ecules in the asymmetric unit. The tetra-hydro-pyridine ring adopts a distorted boat conformation in both mol-ecules and the dihedral angles between the planes of the fluoro-substituted rings are 77.1 (6) and 77.3 (6)°. The amino group and carbonyl O atom are involved in an intra-molecular N-H⋯O hydrogen bond, thereby generating an S(6) ring motif. In the crystal, mol-ecules are linked by C-H⋯F hydrogen bonds forming a three-dimensional network and C-H⋯π inter-actions. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H⋯H (47.9%), C⋯H/H⋯C (30.7%) and F⋯H/H⋯F (12.4%) contacts. The optimized structure calculated using density functional theory (DFT) at the B3LYP/6-311+G(2d,p) level is compared with the experimentally determined molecular structure in the solid state. The HOMO-LUMO behaviour was used to determine the energy gap and the Natural Bond Orbital (NBO) analysis was done to study donor-acceptor interconnections.

Supramolecular interactions in some organic hydrated 2,4,6-triaminopyrimidinium carboxylate and sulfate salts.

Four salts, namely, 2,4,6-triaminopyrimidinium 6-chloronicotinate dihydrate, C4H8N5+·C6H3ClNO2-·2H2O, (I), 2,4,6-triaminopyrimidinediium pyridine-2,6-dicarboxylate dihydrate, C4H9N52+·C7H3NO42-·2H2O, (II), 2,4,6-triaminopyrimidinediium sulfate monohydrate, C4H9N52+·SO42-·H2O, (III), and 2,4,6-triaminopyrimidinium 3,5-dinitrobenzoate dihydrate, C4H8N5+·C7H3N2O6-·2H2O, (IV), were synthesized and characterized by X-ray diffraction techniques. Proton transfer from the corresponding acid to the pyrimidine base has occurred in all four crystal structures. Of the four salts, two [(I) and (IV)] exist as monoprotonated bases and two [(II) and (III)] exist as diprotonated bases. In all four crystal structures, the acid interacts with the pyrimidine base through N-H...O hydrogen bonds, generating an R22(8) ring motif. The sulfate group mimics the role of the carboxylate anions. The water molecules present in compounds (I)-(IV) form water-mediated large ring motifs. The formation of water-mediated interactions in these crystal structures can be used as a model in the study of the hydration of nucleobases. Water molecules play an important role in building supramolecular structures. In addition to these strong hydrogen-bonding interactions, some of the crystal structures are further enriched by aromatic π-π stacking interactions [(I) and (II)].

Late-stage Ligand Modification After Coordination Strengthens Stereoselectively Self-Assembled Hemiaminal Ether Complexes.

Fragile hemiaminal ether linkages present in the backbone of koneramines (LR OR'), tridentate ligands, bound to copper(II) in stereoselectively self-assembled syn-[Cu(LR OR')X2 ] complexes were transformed into sturdy methylene linkages to make corresponding rac-[Cu(LR H)Cl2 ] complexes by late-stage ligand modification after coordination with the retention of coordination sphere. The generality of stereoselective self-assembly of koneramine complexes is shown by utilising a number of metal ions, anions, amines, alcohols and thiols with complete characterisations.

Synthesis, crystal structure and Hirshfeld surface analysis of tert-butyl 4-[4-(di-fluoro-meth-oxy)phen-yl]-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexa-hydro-quinoline-3-carboxyl-ate.

The 1,4-di-hydro-pyridine ring of the title compound, C24H29F2NO4, adopts a distorted boat conformation, while the cyclo-hexene ring is in an almost twist-boat conformation. In the crystal, N-H⋯O and C-H⋯O hydrogen bonds as well as C-H⋯π inter-actions connect mol-ecules, forming layers parallel to the (100) plane. These layers are linked by van der Waals forces and C-H⋯F inter-actions, which consolidate the crystal structure. Hirshfeld surface analysis shows the major contributions to the crystal packing are from H⋯H (54.1%), F⋯H/H⋯F (16.9%), O⋯H/H⋯O (15.4%) and C⋯H/H⋯C (12.6%) contacts.

Catalytic Acceptorless Dehydrogenation (CAD) of Secondary Benzylic Alcohols into Value-Added Ketones Using Pd(II)-NHC Complexes.

For the creation of adaptable carbonyl compounds in organic synthesis, the oxidation of alcohols is a crucial step. As a sustainable alternative to the harmful traditional oxidation processes, transition-metal catalysts have recently attracted a lot of interest in acceptorless dehydrogenation reactions of alcohols. Here, using well-defined, air-stable palladium(II)-NHC catalysts (A-F), we demonstrate an effective method for the catalytic acceptorless dehydrogenation (CAD) reaction of secondary benzylic alcohols to produce the corresponding ketones and molecular hydrogen (H2). Catalytic acceptorless dehydrogenation (CAD) has been successfully used to convert a variety of alcohols, including electron-rich/electron-poor aromatic secondary alcohols, heteroaromatic secondary alcohols, and aliphatic cyclic alcohols, into their corresponding value-added ketones while only releasing molecular hydrogen as a byproduct.

Coordination Behavior of the Tellurium Incorporated Mercuraazametallamacrocycle and Investigation of d10 ⋠⋠⋠d10 Interactions between Closed Shell (Ag+ Hg2+ ) Metal Ions.

Herein, a new tellurium and mercury containing mercuraazametallamacrocycle has been prepared via (2+2) condensation of bis(o-aminophenyl)telluride and bis(o-formylphenyl)mercury(II). The isolated bright yellow solid of mercuraazametallamacrocycle has adopted unsymmetrical figure-of-eight conformation in the crystal structure. To study the metallophilic interactions between closed shell metal ions, the macrocyclic ligand has been treated with two equiv. of AgOTf (OTf=trifluoromethansulfonate) and AgBF4 , which afforded greenish-yellow bimetallic silver complexes. The isolated silver complexes displayed intramolecular Hg⋅⋅⋅Ag, Te⋅⋅⋅Ag interactions as well as intermolecular Hg⋅⋅⋅Hg interactions and formed an extended 1D molecular chain by directing six atoms to interact as TeII ⋅⋅⋅AgI ⋅⋅⋅HgII ⋅⋅⋅HgII ⋅⋅⋅AgI ⋅⋅⋅TeII in a non linear fashion. The Hg⋅⋅⋅Ag, Te⋅⋅⋅Ag interactions have also been studied in solution by 199 Hg, 125 Te NMR spectroscopy, absorption, and emission spectroscopy. In DFT calculations, the Atom in Molecule (AIM) analysis, non-covalent interactions (NCI), natural bonding orbital (NBO) analysis strongly supported for experimental evidences and revealed that the intermolecular Hg⋅⋅⋅Hg interaction is stronger than the intramolecular Hg⋅⋅⋅Ag interactions.

Syntheses and crystal structures of three salts of 1-(4-nitro-phenyl)-piperazine.

The crystal structures and Hirshfeld surface analyses of three salts of 1-(4-nitro-phenyl)-piperazine with 2-chloro-benzoic acid, 2-bromo-benzoic acid and 2-iodo-benzoic acid are reported. The chloro-benzoate salt, C10H14N3O2 +·C7H4ClO2 -, contains whole-ion-disordered cations and anions, which were modeled with two equivalent conformations with occupancies of 0.745 (10)/0.255 (10) and 0.563 (13)/0.437 (13), respectively. The bromo-benzoate and iodo-benzoate derivatives are isomorphous and crystallize as hemihydrates, viz. C10H14N3O2 +·C7H4BrO2 -·0.5H2O and C10H14N3O2 +·C7H4IO2 -·0.5H2O, respectively [the water mol-ecule is disordered over two locations with occupancies of 0.276 (3)/0.223 (3) for the iodo-benzoate derivative]. In the extended structures, all three salts feature an R 4 4(12) loop of two anions and two cations linked by N-H⋯O hydrogen bonds.

Pushing the Boundary of Covalency in Lanthanoid-Tellurium Bonds: Insights from the Synthesis, Molecular and Electronic Structures of Low-Coordinate, Monomeric Europium(II) and Ytterbium(II) Tellurolates.

Owing to the strict hard/soft dichotomy between the lanthanoids and tellurium atoms, and the strong affinity of lanthanoid ions for high coordination numbers, low-coordinate, monomeric lanthanoid tellurolate complexes have remained elusive as compared to the lanthanoid complexes with lighter group 16 elements (O, S, and Se). This makes the development of suitable ligand systems for low-coordinate, monomeric lanthanoid tellurolate complexes an appealing endeavor. In a first report, a series of low-coordinate, monomeric lanthanoid (Yb, Eu) tellurolate complexes were synthesized by utilizing hybrid organotellurolate ligands containing N-donor pendant arms. The reaction of bis[2-((dimethylamino)methyl)phenyl] ditelluride, 1 and 8,8'diquinolinyl ditelluride, 2 with Ln0 metals (Ln=Eu, Yb) resulted in the formation of monomeric complexes [LnII (TeR)2 (Solv)2 ] [R=C6 H4 -2-CH2 NMe2 ] [3: Ln=Eu, Solv=tetrahydrofuran; 4: Ln=Eu, Solv=acetonitrile; 5: Ln=Yb, Solv=tetrahydrofuran; 6: Ln=Yb, Solv=pyridine] and [EuII (TeNC9 H6 )2 (Solv)n ] (7: Solv=tetrahydrofuran, n=3; 8: Solv=1,2-dimethoxyethane, n=2), respectively. Complexes 3-4 and 7-8 represent the first sets of examples of monomeric europium tellurolate complexes. The molecular structures of complexes 3-8 are validated by single-crystal X-ray diffraction studies. The electronic structures of these complexes were investigated using Density Functional Theory (DFT) calculations, which revealed appreciable covalency between the tellurolate ligands and lanthanoids.

5-([(Z)-Meth-oxy-imino]{2-[(2-methyl-phen-oxy)meth-yl]phen-yl}meth-yl)-1,3,4-oxa-diazole-2(3H)-thione dimethyl sulfoxide monosolvate.

The title compound, C18H17N3O3S·C2H6OS, crystallizes in the monoclinic space group P21 /c. In the crystal, C 1 1(9) chains of C-H⋯O inter-actions are formed, propogating in the c-axis direction. The N-H hydrogen atom forms a strong hydrogen bond with the oxygen atom of a DMSO solvate mol-ecule.

Syntheses, crystal structures and Hirshfeld surface analysis of three salts of 1-(4-nitro-phenyl)-piperazine.

The structures and Hirshfeld surface analysis of three salts of 1-(4-nitro-phenyl)-piperazine are discussed. In 4-(4-nitro-phen-yl)piperazin-1-ium salicylate (C10H14N3O2 +·C7H5O3 -), there are strong hydrogen bonds between cation and anion and the 4-nitro-phenyl substituent occupies an equatorial position in the piperazinium ring. The cation and anion are linked together by supra-molecular inter-actions [graph-set notation of hydrogen bonding (6) propagating in the a-axis direction]. Additionally, there is π-π stacking involving the salicylate anion and the piperazinium cation in adjacent asymmetric units as well as a C-H⋯π inter-action between a hydrogen atom on the piperazine ring and the phenyl ring within the salicyclate anion. In bis-[4-(4-nitro-phen-yl)piperazin-1-ium] bis-(4-fluoro-benzoate) trihydrate (2C10H14N3O2 +·2C7H4FO2 -·3H2O), there are two cations, two anions, and three water mol-ecules of solvation in the asymmetric unit, all linked by hydrogen bonds [graph-set notation of hydrogen bonding R 2 2(20) between adjacent cations and R 3 3(9) between a cation and its adjacent anion]. In the anion, the 4-nitro-phenyl ring occupies an axial substitution position in the piperazinium ring, which is relatively rare. Within the asymmetric unit, the phenyl groups in the cations show an offset π-π inter-action. Additionally, there is a C-H⋯π inter-action between a hydrogen atom on the phenyl ring within a cation and the phenyl ring within an anion. In 4-(4-nitro-phen-yl)piperazin-1-ium 3,5-di-nitro-benzoate (C10H14N3O2 +·C7H4N2O6 -), there is a strong N-H⋯O hydrogen bond linking the cation and anion and the 4-nitro-phenyl ring occupies an axial substitution position in the piperazinium ring, as seen in the previous structure. In the crystal, the cation and the anion form a complex three-dimensional hydrogen-bonded array involving R 2 2(8), R 4 4(12) and R 4 4(20) rings propogating in the a-axis direction. The nitro-phenyl group is disordered with occupancies of 0.806 (10) and 0.194 (10).

Crystal structure and Hirshfeld surface analysis of isopropyl 4-[2-fluoro-5-(tri-fluoro-meth-yl)phen-yl]-2,6,6-trimethyl-5-oxo-1,4,5,6,7,8-hexa-hydro-quinoline-3-carboxyl-ate.

In the title compound, C23H25F4NO3, the 1,4-di-hydro-pyridine ring adopts a distorted boat conformation, while the cyclo-hexene ring is almost showing a half-chair conformation. In the crystal, inter-molecular N-H⋯O hydrogen bonds connect the mol-ecules into chains with graph-set motif C(6) parallel to the a-axis. These chains are linked together by C-H⋯O and C-H⋯F inter-actions, forming a three-dimensional network. In addition, C-H⋯π inter-actions link the mol-ecules into layers parallel to the (100) plane. A Hirshfeld surface analysis was performed to further investigate the inter-molecular inter-actions.

Synthesis and structures of dinuclear palladium complexes with 1,3-benzimidazolidine-2-thione and 1,3-imidazoline-2-thione.

The synthesis and structures of dinuclear palladium complexes with 1,3-benz-imidazolidine-2-thione (bzimtH) and 1,3-imidazoline-2-thione (imtH) are reported, namely, bis-(µ-1H-benzimidazole-2-thiol-ato)-κ2 N 3:S;κ2 S:N 3-bis-[cyanido(tri-phenyl-phosphine-κP)palladium(II)], [Pd2(C7H5N2S)2(CN)2(C18H15P)2] or [Pd2(µ-N,S-bzimtH)2(CN)2(PPh3)2] (1), and bis-(µ-1H-imidazole-2-thiol-ato)-κ2 N 3:S;κ2 S:N 3-bis-[cyanido(tri-phenyl-phosphine-κP)palladium(II)] aceto-nitrile 0.58-solvate, [Pd2(C3H3N2S)2(CN)2(C18H15P)2]·0.58C2H3N or [Pd2(µ-N,S-imtH)2(CN)2(PPh3)2]·0.58C2H3N (2). The compound [Pd2(µ-N,S-bzimtH)2(CN)2(PPh3)2] is located on a crystallographic twofold axis while [Pd2(µ-N,S-imtH)2(CN)2(PPh3)2]. 0.58(C2H3N) contains two partially occupied aceto-nitrile solvent mol-ecules with occupancies of 0.25 and 0.33. In both of these compounds, the anionic bzimtH- and imtH- ligands coordinate through N,S-donor atoms in a bridging mode, covering four coordination sites of two metal centers and other two sites are occupied by two PPh3 ligand mol-ecules. Finally, the remaining two sites of two metal centers are occupied by cyano groups, abstracted by the metals from the solvent during reaction. In the packing of the 1,3-benzimidazolidine- 2-thione and 1,3-imidazoline-2-thione complexes, there are intra-molecular π-π inter-actions involving the thione moiety as well as an N-H⋯N hydrogen bond linking the thione and cyano ligands. In addition, in 2, as well as the π-π inter-action involving the thione moieties, there is an additional π-π inter-action involving one of the thione moieties and an adjacent phenyl ring from the tri-phenyl-phosphine ligand. There are also C-H⋯N inter-actions between the imidazoline rings and the aceto-nitrile N atoms.

Supramolecular interactions in salts/cocrystals involving pyrimidine derivatives of sulfonate/carboxylic acid.

The crystal structures of three compounds involving aminopyrimidine derivatives are reported, namely, 5-fluorocytosinium sulfanilate-5-fluorocytosine-4-azaniumylbenzene-1-sulfonate (1/1/1), C4H5FN3O+·C6H6NO3S-·C4H4FN3O·C6H7NO3S, I, 5-fluorocytosine-indole-3-propionic acid (1/1), C4H4FN3O·C11H11NO2, II, and 2,4,6-triaminopyrimidinium 3-nitrobenzoate, C4H8N5+·C7H4NO4-, III, which have been synthesized and characterized by single-crystal X-ray diffraction. In I, there are two 5-fluorocytosine (5FC) molecules (5FC-A and 5FC-B) in the asymmetric unit, with one of the protons disordered between them. 5FC-A and 5FC-B are linked by triple hydrogen bonds, generating two fused rings [two R22(8) ring motifs]. The 5FC-A molecules form a self-complementary base pair [R22(8) ring motif] via a pair of N-H...O hydrogen bonds and the 5FC-B molecules form a similar complementary base pair [R22(8) ring motif]. The combination of these two types of pairing generates a supramolecular ribbon. The 5FC molecules are further hydrogen bonded to the sulfanilate anions and sulfanilic acid molecules via N-H...O hydrogen bonds, generating R44(22) and R66(36) ring motifs. In cocrystal II, two types of base pairs (homosynthons) are observed via a pair of N-H...O/N-H...N hydrogen bonds, generating R22(8) ring motifs. The first type of base pair is formed by the interaction of an N-H group and the carbonyl O atom of 5FC molecules through a couple of N-H...O hydrogen bonds. Another type of base pair is formed via the amino group and a pyrimidine ring N atom of the 5FC molecules through a pair of N-H...N hydrogen bonds. The base pairs (via N-H...N hydrogen bonds) are further bridged by the carboxyl OH group of indole-3-propionic acid and the O atom of 5FC through O-H...O hydrogen bonds on either side of the R22(8) motif. This leads to a DDAA array. In salt III, one of the N atoms of the pyrimidine ring is protonated and interacts with the carboxylate group of the anion through N-H...O hydrogen bonds, leading to the primary ring motif R22(8). Furthermore, the 2,4,6-triaminopyrimidinium (TAP) cations form base pairs [R22(8) homosynthon] via N-H...N hydrogen bonds. A carboxylate O atom of the 3-nitrobenzoate anion bridges two of the amino groups on either side of the paired TAP cations to form another ring [R32(8)]. This leads to the generation of a quadruple DADA array. The crystal structures are further stabilized by π-π stacking (I and III), C-H...π (I and II), C-F...π (I) and C-O...π (II) interactions.

Synthesis, characterization, crystal structure and Hirshfeld surface analysis of isobutyl 4-[4-(di-fluoro-meth-oxy)phen-yl]-2,6,6-trimethyl-5-oxo-1,4,5,6,7,8-hexa-hydro-quinoline-3-carboxyl-ate.

In the title compound, C24H29F2NO4, which crystallizes in the ortho-rhom-bic Pca21 space group with Z = 4, the 1,4-di-hydro-pyridine ring adopts a distorted boat conformation, while the cyclo-hexene ring is in a distorted half-chair conformation. In the crystal, the mol-ecules are linked by N-H⋯O and C-H⋯O inter-actions, forming supra-molecular chains parallel to the a axis. These chains pack with C-H⋯π inter-actions between them, forming layers parallel to the (010) plane. The cohesion of the crystal structure is ensured by van der Waals inter-actions between these layers. Hirshfeld surface analysis shows the major contributions to the crystal packing are from H⋯H (56.9%), F⋯H/H⋯F (15.7%), O⋯H/H⋯O (13.7%) and C⋯H/H⋯C (9.5%) contacts.

Synthesis of cobalt(II) phenolate selenoether complexes to mimic hydrogenase-like activity for hydrogen gas production.

Selenium-derived electrocatalysts have been well explored for electrocatalytic hydrogen evolution reactions to mimic hydrogenase-like activity; however, the stability of these synthetic mimics is yet to be enhanced. In this study, we report the synthesis and characterization of a series of 1,10-phenanthroline-cobalt(II) phenolate selenoether complexes using 1,10-phenanthroline and 6-nitro-1,10-phenanthroline-Co(II)-dichloride and substituted bis-selenophenolate ligands. The synthesized cobalt(II) phenolate selenoether complexes have been characterized by CHN analysis, mass spectrometry, single crystal XRD, and UV-visible absorption spectroscopy. These complexes show electrocatalytic proton reduction from acetic acid at an overpotential of 0.45-0.56 V vs. Fc+/Fc and surpass previously reported selenium and sulfur-containing electrocatalysts. Furthermore, gas analysis from control potential electrolysis confirms that the cobalt(II) selenoethers act as electrocatalysts to produce H2 with a faradaic efficiency of 43-83% and show a turnover number of 3.24-58.60 molcat-1. The hydrogen evolution reaction (HER) was probed using deuterated acetic acid, which demonstrates an inverse kinetic isotopic effect (KIE) and is consistent with the formation of metal hydride intermediates. Furthermore, control experiments (post-dip analysis and multiple CV studies) have been performed to support the catalysis being due to a homogeneous process. Acid titration using UV-visible spectroscopy reveals that protonation is the prior step for electrocatalysis and assists in the formation of a cobalt hydride intermediate, which upon reaction with a proton generates hydrogen gas.

5-(4-Fluoro-phen-yl)-1-[4-(4-methyl-phen-yl)thia-zol-2-yl]-3-[4-(prop-2-yn-yloxy)phen-yl]-4,5-di-hydro-1H-pyrazole.

In the title compound, C28H22FN3OS, four rings are almost coplanar, with the fluorophenyl ring substantially twisted. In the extended structure, aromatic π-π stacking inter-actions between the pyrazole ring and the tolyl ring link the mol-ecules into centrosymmetric dimers.