Novel Benzyl‐ or 4‐Cyanobenzyl‐Substituted N‐Heterocyclic (Bromo)(carbene)silver(I) and (Carbene)(chloro)gold(I) Complexes: Synthesis and Preliminary Cytotoxicity Studies

N‐Heterocyclic carbene (NHC) complexes bromo(1,3‐dibenzyl‐1,3‐dihydro‐2H‐imidazol‐2‐ylidene)silver(I) ( 2a ), bromo[1‐(4‐cyanobenzyl)‐3‐methyl‐1,3‐dihydro‐2H‐imidazol‐2‐ylidene]silver(I) ( 2b ), and bromo[1‐(4‐cyanobenzyl)‐3‐methyl‐1,3‐dihydro‐2H‐benzimidazol‐2‐ylidene]silver(I) ( 2c ) were prepared by the reaction of 1,3‐dibenzyl‐1H‐imidazol‐3‐ium bromide ( 1a ), 3‐(4‐cyanobenzyl)‐1‐methyl‐1H‐imidazol‐3‐ium bromide ( 1b ), and 3‐(4‐cyanobenzyl)‐1‐methyl‐1H‐benzimidazol‐3‐ium bromide ( 1c ), respectively, with silver(I) oxide. NHC Complexes chloro(1,3‐dibenzyl‐1,3‐dihydro‐2H‐imidazol‐2‐ylidene)gold(I) ( 3a ), chloro[1‐(4‐cyanobenzyl)‐3‐methyl‐1,3‐dihydro‐2H‐imidazol‐2‐ylidene]gold(I) ( 3b ), and chloro[1‐(4‐cyanobenzyl)‐3‐methyl‐1,3‐dihydro‐2H‐benzimidazol‐2‐ylidene]gold(I) ( 3c ) were prepared via transmetallation of corresponding (bromo)(NHC)silver(I) complexes with chloro(dimethylsulfido)gold(I). The complex 3a was characterized in two polymorphic forms by single‐crystal X‐ray diffraction showing two rotamers in the solid state. The cytotoxicities of all three bromo(NHC)silver(I) complexes and three (chloro)(NHC)gold(I) complexes were investigated through 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl‐2H‐tetrazolium bormide (MTT)‐based preliminary in vitro testing on the Caki‐1 cell line in order to determine their IC₅₀ values. (Bromo)(NHC)silver(I) complexes 2a – 2c and (chloro)(NHC)gold(I) complexes 3a – 3c were found to have IC₅₀ values of 27±2, 28±2, 34±6, 10±1, 12±5, and 12±3 μM , respectively, on the Caki‐1 cell line.     

Synthese und Reaktivität von 2‐Brom‐1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol Molekülstruktur von Bis(1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol‐2‐yl)

Synthesis and Reactivity of 2‐Bromo‐1,3‐diethyl‐2,3‐dihydro‐1 H ‐1,3,2‐benzodiazaborole Molecular Structure of Bis(1,3‐diethyl‐2,3‐dihydro‐1 H ‐1,3,2‐benzodiazaborol‐2‐yl The reaction of a slurry of calcium hydride in toluene with N,N′‐diethyl‐o‐phenylenediamine ( 1 ) and boron tribromide affords 2‐bromo‐1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol ( 2 ) as a colorless oil. Compound 2 is converted into 2‐cyano‐1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborole ( 3 ) by treatment with silver cyanide in acetonitrile. Reaction of 2 with an equimolar amount of methyllithium affords 1,3‐diethyl‐2‐methyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborole ( 4 ). 1,3,2‐Benzodiazaborole is smoothly reduced by a potassium‐sodium alloy to yield bis(1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol‐2‐yl] ( 7 ), which crystallizes from n‐pentane as colorless needles. Compound 7 is also obtained from the reaction of 2 and LiSnMe₃ instead of the expected 2‐trimethylstannyl‐1,3,2‐benzodiazaborole. N,N′‐Bis(1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol‐2‐ yl)‐1,2‐diamino‐ethane ( 6 ) results from the reaction of 2 with Li(en)C≡CH as the only boron containing product. Compounds 2 – 4 , 6 and 7 are characterized by means of elemental analyses and spectroscopy (IR, ¹H‐, ¹¹B{¹H}‐, ¹³C{¹H}‐NMR, MS). The molecular structure of 7 was elucidated by X‐ray diffraction analysis.     

A structural study of 4‐aminoantipyrine and six of its Schiff base derivatives

Six derivatives of 4‐amino‐1,5‐dimethyl‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazol‐3‐one (4‐aminoantipyrine), C₁₁H₁₃N₃O, (I), have been synthesized and structurally characterized to investigate the changes in the observed hydrogen‐bonding motifs compared to the original 4‐aminoantipyrine. The derivatives were synthesized from the reactions of 4‐aminoantipyrine with various aldehyde‐, ketone‐ and ester‐containing molecules, producing (Z)‐methyl 3‐[(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazol‐4‐yl)amino]but‐2‐enoate, C₁₆H₁₉N₃O₃, (II), (Z)‐ethyl 3‐[(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazol‐4‐yl)amino]but‐2‐enoate, C₁₇H₂₁N₃O₃, (III), ethyl 2‐[(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazol‐4‐yl)amino]cyclohex‐1‐enecarboxylate, C₂₀H₂₅N₃O₃, (IV), (Z)‐ethyl 3‐[(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazol‐4‐yl)amino]‐3‐phenylacrylate, C₂₂H₂₃N₃O₃, (V), 2‐cyano‐N‐(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazol‐4‐yl)acetamide, C₁₄H₁₄N₄O₂, (VI), and (E)‐methyl 4‐{[(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazol‐4‐yl)amino]methyl}benzoate, C₂₀H₁₉N₃O₃, (VII). The asymmetric units of all these compounds have one molecule on a general position. The hydrogen bonding in (I) forms chains of molecules via intermolecular N—H...O hydrogen bonds around a crystallographic sixfold screw axis. In contrast, the formation of enamines for all derived compounds except (VII) favours the formation of a six‐membered intramolecular N—H...O hydrogen‐bonded ring in (II)–(V) and an intermolecular N—H...O hydrogen bond in (VI), whereas there is an intramolecular C—H...O hydrogen bond in the structure of imine (VII). All the reported compounds, except for (II), feature π–π interactions, while C—H...π interactions are observed in (II), C—H...O interactions are observed in (I), (III), (V) and (VI), and a C—O...π interaction is observed in (II).     

An Efficient Synthesis of 3‐(3‐benzyl‐2‐(phenylimino)‐2,3‐dihydrothiazol‐4‐yl)‐6‐methyl‐4‐(2‐oxo‐2‐phenylethoxy)‐3,4‐dihydro‐2H‐pyran‐2‐one Derivatives via Multi‐Component Approach

An easy, highly efficient and a new convenient one‐pot, two‐step approach to the synthesis of 3‐(3‐benzyl‐2‐(phenylimino)‐2,3‐dihydrothiazol‐4‐yl)‐6‐methyl‐4‐(2‐oxo‐2‐phenylethoxy)‐3,4‐dihydro‐2H‐pyran‐2‐one is described. These compounds were synthesized from 3‐(3‐benzyl‐2‐(phenylimino)‐2,3‐dihydrothiazol‐4‐yl)‐4‐hydroxy‐6‐methyl‐3,4‐dihydro‐2H‐pyran‐2‐one and α‐bromoketones in good yields. The compounds 4 were synthesized by a multi‐component reaction between 1 , 2 , and 3 and the prominent features of this protocol are mild reaction conditions, operation simplicity, and good to high yields of products.     

Three AgI,CuI and CdII coordination polymers based on the new asymmetrical ligand 2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole: syntheses,characterization and emission properties

The new asymmetrical organic ligand 2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole ( L , C₁₇H₁₃N₅O), containing pyridine and imidazole terminal groups, as well as potential oxdiazole coordination sites, was designed and synthesized. The coordination chemistry of L with soft Ag^I, Cu^I and Cd^II metal ions was investigated and three new coordination polymers (CPs), namely, catena‐poly[[silver(I)‐μ‐2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole] hexafluoridophosphate], {[Ag( L )]PF₆}_n, catena‐poly[[copper(I)‐di‐μ‐iodido‐copper(I)‐bis(μ‐2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole)] 1,4‐dioxane monosolvate], {[Cu₂I₂( L )₂]·C₄H₈O₂}_n, and catena‐poly[[[dinitratocopper(II)]‐bis(μ‐2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole)]–methanol–water (1/1/0.65)], {[Cd( L )₂(NO₃)₂]·2CH₄O·0.65H₂O}_n, were obtained. The experimental results show that ligand L coordinates easily with linear Ag^I, tetrahedral Cu^I and octahedral Cd^II metal atoms to form one‐dimensional polymeric structures. The intermediate oxadiazole ring does not participate in the coordination interactions with the metal ions. In all three CPs, weak π–π interactions between the nearly coplanar pyridine, oxadiazole and benzene rings play an important role in the packing of the polymeric chains.     

Four NiII complexes with the new cyclam–methylimidazole ligand 1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane

Although it has not proved possible to crystallize the newly prepared cyclam–methylimidazole ligand 1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane (L^Im1), the trans and cis isomers of an Ni^II complex, namely trans‐aqua{1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}nickel(II) bis(perchlorate) monohydrate, [Ni(C₁₅H₃₀N₆)(H₂O)](ClO₄)₂·H₂O, (1), and cis‐aqua{1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}nickel(II) bis(perchlorate), [Ni(C₁₅H₃₀N₆)(H₂O)](ClO₄)₂, (2), have been prepared and structurally characterized. At different stages of the crystallization and thermal treatment from which (1) and (2) were obtained, a further two compounds were isolated in crystalline form and their structures also analysed, namely trans‐{1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}(perchlorato)nickel(II) perchlorate, [Ni(ClO₄)(C₁₅H₃₀N₆)]ClO₄, (3), and cis‐{1,8‐bis[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}nickel(II) bis(perchlorate) 0.24‐hydrate, [Ni(C₂₀H₃₆N₆)](ClO₄)₂·0.24H₂O, (4); the 1,8‐bis[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane ligand is a minor side product, probably formed in trace amounts in the synthesis of L^Im1. The configurations of the cyclam macrocycles in the complexes have been analysed and the structures are compared with analogues from the literature.     

Synthesis,structure and in vitro cytotoxicity testing of some 1,3,4‐oxadiazoline derivatives from 2‐hydroxy‐5‐iodobenzoic acid

The syntheses of nine new 5‐iodosalicylic acid‐based 1,3,4‐oxadiazoline derivatives starting from methyl salicylate are described. These compounds are 2‐[4‐acetyl‐5‐methyl‐5‐(3‐nitrophenyl)‐4,5‐dihydro‐1,3,4‐oxadiazol‐2‐yl]‐4‐iodophenyl acetate ( 6a ), 2‐[4‐acetyl‐5‐methyl‐5‐(4‐nitrophenyl)‐4,5‐dihydro‐1,3,4‐oxadiazol‐2‐yl]‐4‐iodophenyl acetate ( 6b ), 2‐(4‐acetyl‐5‐methyl‐5‐phenyl‐4,5‐dihydro‐1,3,4‐oxadiazol‐2‐yl)‐4‐iodophenyl acetate, C₁₉H₁₇IN₂O₄ ( 6c ), 2‐[4‐acetyl‐5‐(4‐fluorophenyl)‐5‐methyl‐4,5‐dihydro‐1,3,4‐oxadiazol‐2‐yl]‐4‐iodophenyl acetate, C₁₉H₁₆FIN₂O₄ ( 6d ), 2‐[4‐acetyl‐5‐(4‐chlorophenyl)‐5‐methyl‐4,5‐dihydro‐1,3,4‐oxadiazol‐2‐yl]‐4‐iodophenyl acetate, C₁₉H₁₆ClIN₂O₄ ( 6e ), 2‐[4‐acetyl‐5‐(3‐bromophenyl)‐5‐methyl‐4,5‐dihydro‐1,3,4‐oxadiazol‐2‐yl]‐4‐iodophenyl acetate ( 6f ), 2‐[4‐acetyl‐5‐(4‐bromophenyl)‐5‐methyl‐4,5‐dihydro‐1,3,4‐oxadiazol‐2‐yl]‐4‐iodophenyl acetate ( 6g ), 2‐[4‐acetyl‐5‐methyl‐5‐(4‐methylphenyl)‐4,5‐dihydro‐1,3,4‐oxadiazol‐2‐yl]‐4‐iodophenyl acetate ( 6h ) and 2‐[5‐(4‐acetamidophenyl)‐4‐acetyl‐5‐methyl‐4,5‐dihydro‐1,3,4‐oxadiazol‐2‐yl]‐4‐iodophenyl acetate ( 6i ). The compounds were characterized by mass, ¹H NMR and ¹³C NMR spectroscopies. Single‐crystal X‐ray diffraction studies were also carried out for 6c , 6d and 6e . Compounds 6c and 6d are isomorphous, with the 1,3,4‐oxadiazoline ring having an envelope conformation, where the disubstituted C atom is the flap. The packing is determined by C—H…O, C—H…π and I…π interactions. For 6e , the 1,3,4‐oxadiazoline ring is almost planar. In the packing, Cl…π interactions are observed, while the I atom is not involved in short interactions. Compounds 6d , 6e , 6f and 6h show good inhibiting abilities on the human cancer cell lines KB and Hep‐G2, with IC₅₀ values of 0.9–4.5 µM.     

Temperature‐induced solid‐to‐solid transformation in helical homochiral coordination polymers

The reactions of (R)‐ and (S)‐4‐(1‐carboxyethoxy)benzoic acid (H₂CBA) with 1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene (1,3‐BMIB) ligands afforded a pair of homochiral coordination polymers (CPs), namely, poly[[[μ‐1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene][μ‐(S)‐4‐(1‐carboxylatoethoxy)benzoato]zinc(II)] monohydrate], {[Zn(C₁₀H₈O₅)(C₁₄H₁₄N₄)]·H₂O}_n or {[Zn{(S)‐CBA}(1,3‐BMIB)]·H₂O}_n ( 1‐L ), and poly[[[μ‐1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene][μ‐(R)‐4‐(1‐carboxylatoethoxy)benzoato]zinc(II)] monohydrate] ( 1‐D ). Three kinds of helical chains exist in compounds 1‐D and 1‐L , which are constructed from Zn^II atoms, 1,3‐BMIB ligands and/or CBA^2? ligands. When the as‐synthesized crystals of 1‐L and 1‐D were further heated in the mother liquor or air, poly[[μ‐1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene][μ‐(S)‐4‐(1‐carboxylatoethoxy)benzoato]zinc(II)], [Zn(C₁₀H₈O₅)(C₁₄H₁₄N₄)]_n or [Zn{(S)‐CBA}(1,3‐BMIB)]_n ( 2‐L ), and poly[[μ‐1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene][μ‐(R)‐4‐(1‐carboxylatoethoxy)benzoato]zinc(II)] ( 2‐D ) were obtained, respectively. The single‐crystal structure analysis revealed that 2‐L and 2‐D only contained one type of helical chain formed by Zn^II atoms and 1,3‐BMIB and CBA^2? ligands, which indicated that the helical chains were reconstructed though solid‐to‐solid transformation. This result not only means the realization of helical transformation, but also gives a feasible strategy to build homochiral CPs.     

New Approaches to the Synthesis of 4‐(2‐Aminophenyl)‐1,3‐dihydro‐2H‐imidazol‐2‐ones and 3‐Ureidoindoles and a Study of Their Interconversion

3‐Alkyl/aryl‐3‐ureido‐1H,3H‐quinoline‐2,4‐diones ( 2 ) and 3a‐alkyl/aryl‐9b‐hydroxy‐3,3a,5,9b‐tetrahydro‐1H‐imidazo[4,5‐c]quinoline‐2,4‐diones ( 3 ) react in boiling concentrated HCl to give 5‐alkyl/aryl‐4‐(2‐aminophenyl)‐1,3‐dihydro‐2H‐imidazol‐2‐ones ( 6 ). The same compounds were prepared by the same procedure from 2‐alkyl/aryl‐3‐ureido‐1H‐indoles ( 4 ), which were obtained from the reaction of 3‐alkyl/aryl‐3‐aminoquinoline‐2,4(1H,3H)‐diones ( 1 ) with 1,3‐diphenylurea or by the transformation of 3a‐alkyl/aryl‐9b‐hydroxy‐3,3a,5,9b‐tetrahydro‐1H‐imidazo[4,5‐c]quinoline‐2,4‐diones ( 3 ) and 5‐alkyl/aryl‐4‐(2‐aminophenyl)‐1,3‐dihydro‐2H‐imidazol‐2‐ones ( 6 ) in boiling AcOH. The latter were converted into 1,3‐bis[2‐(2‐oxo‐2,3‐dihydro‐1H‐imidazol‐4‐yl)phenyl]ureas ( 5 ) by treatment with triphosgene. All compounds were characterized by ¹H‐ and ¹³C‐NMR and IR spectroscopy, as well as atmospheric pressure chemical‐ionisation mass spectra.     

Two new NiII and ZnII metal–organic frameworks of glutarate and 1,4‐bis[(2‐methyl‐1H‐imidazol‐1‐yl)methyl]benzene ligands: syntheses,structures and luminescence sensing properties

Two new metal–organic frameworks (MOFs), namely, three‐dimensional poly[diaquabis{μ₂‐1,4‐bis[(2‐methyl‐1H‐imidazol‐1‐yl)methyl]benzene}bis(μ₂‐glutarato)dinickel(II)] monohydrate], {[Ni₂(C₅H₆O₄)₂(C₁₆H₁₈N₄)₂(H₂O)₂]·H₂O}_n or {[Ni₂(Glu)₂(1,4‐mbix)₂(H₂O)₂]·H₂O}_n, ( I ), and two‐dimensional poly[[{μ₂‐1,4‐bis[(2‐methyl‐1H‐imidazol‐1‐yl)methyl]benzene}(μ₂‐glutarato)zinc(II)] tetrahydrate], {[Zn(C₅H₆O₄)(C₁₆H₁₈N₄)]·4H₂O}_n or {[Zn(Glu)(1,4‐mbix)]·4H₂O}_n ( II ), have been synthesized hydrothermally using glutarate (Glu^2?) mixed with 1,4‐bis[(2‐methyl‐1H‐imidazol‐1‐yl)methyl]benzene (1,4‐mbix), and characterized by single‐crystal X‐ray diffraction, IR and UV–Vis spectroscopy, powder X‐ray diffraction, and thermogravimetric and photoluminescence analyses. Ni^II MOF ( I ) shows a 4‐connected 3D framework with point symbol 6⁶, but is not a typical dia network. Zn^II MOF ( II ) displays a two‐dimensional 4⁴‐ sql network with one‐dimensional water chains penetrating the grids along the c direction. The solid‐state photoluminescence analysis of ( II ) was performed at room temperature and the MOF exhibits highly selective sensing toward Fe³⁺ and Cr₂O₇^2? ions in aqueous solution.     

Structural studies and antileishmanial activity of 2‐acetylpyridine and 2‐benzoylpyridine nitroimidazole‐derived hydrazones

Three imidazole hydrazone compounds, namely 2‐(4‐nitro‐1H‐imidazol‐1‐yl)‐N′‐[1‐(pyridin‐2‐yl)ethylidene]acetohydrazide, C₁₂H₁₂N₆O₃, ( 1 ), 2‐(2‐nitro‐1H‐imidazol‐1‐yl)‐N′‐[1‐(pyridin‐2‐yl)ethylidene]acetohydrazide, C₁₂H₁₂N₆O₃, ( 2 ), and 2‐(2‐nitro‐1H‐imidazol‐1‐yl)‐N′‐[(phenyl)(pyridin‐2‐yl)methylidene]acetohydrazide, C₁₇H₁₄N₆O₃, ( 3 ), were obtained and fully characterized, including their crystal structure determinations. While all the compounds proved not to be cytotoxic to J774.A1 macrophage cells, ( 1 ) and ( 3 ) exhibited activity against Leishmania chagasi, whereas ( 2 ) was revealed to be inactive. Since both ( 1 ) and ( 3 ) exhibited antileishmanial effects, while ( 2 ) was devoid of activity, the presence of the acetyl or benzoyl groups was possibly not a determining factor in the observed antiprotozoal activity. In contrast, since ( 1 ) and ( 3 ) are 4‐nitroimidazole derivatives and ( 2 ) is a 2‐nitroimidazole‐derived compound, the presence of the 4‐nitro group probably favours antileishmanial activity over the 2‐nitro group. The results suggested that further investigations on compounds ( 1 ) and ( 3 ) as bioreducible antileishmanial prodrug candidates are called for.     

Controllable assembly of a three‐dimensional metal–organic supramolecular framework displaying hydrogen‐bonding and π–π stacking interactions

The complex poly[[aqua(μ₂‐phthalato‐κ²O¹:O²){μ₃‐2‐[3‐(pyridin‐2‐yl)‐1H‐pyrazol‐1‐yl]acetato‐κ⁴N²,N³:O:O′}{μ₂‐2‐[3‐(pyridin‐2‐yl)‐1H‐pyrazol‐1‐yl]acetato‐κ³N²,N³:O}dizinc(II)] dihydrate], {[Zn₂(C₁₀H₈N₃O₂)₂(C₈H₄O₄)(H₂O)]·2H₂O}_n, has been prepared by solvothermal reaction of 2‐[3‐(pyridin‐2‐yl)‐1H‐pyrazol‐1‐yl]acetonitrile (PPAN) with zinc(II). Under hydrothermal conditions, PPAN is hydrolyzed to 2‐[3‐(pyridin‐2‐yl)‐1H‐pyrazol‐1‐yl]acetate (PPAA⁻). The structure determination reveals that the complex is a one‐dimensional double chain containing cationic [Zn₄(PPAA)₄]⁴⁺ structural units, which are further extended by bridging phthalate ligands. The one‐dimensional chains are extended into a three‐dimensional supramolecular architecture via hydrogen‐bonding and π–π stacking interactions.     

A concise and efficient synthesis of amino‐substituted (1H‐benzo[d]imidazol‐1‐yl)pyrimidine hybrids: synthetic sequence and the molecular and supramolecular structures of six examples

A concise and efficient synthesis of a series of amino‐substituted benzimidazole–pyrimidine hybrids has been developed, starting from the readily available N⁴‐(2‐aminophenyl)‐6‐methoxy‐5‐nitrosopyrimidine‐2,4‐diamine. In each of N⁵‐benzyl‐6‐methoxy‐4‐(2‐phenyl‐1H‐benzo[d]imidazol‐1‐yl)pyrimidine‐2,5‐diamine, C₂₅H₂₂N₆O, (I), 6‐methoxy‐N⁵‐(4‐methoxybenzyl)‐4‐[2‐(4‐methoxyphenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidine‐2,5‐diamine, C₂₇H₂₆N₆O₃, (III), 6‐methoxy‐N⁵‐(4‐nitrobenzyl)‐4‐[2‐(4‐nitrophenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidine‐2,5‐diamine, C₂₅H₂₀N₈O₅, (IV), the molecules are linked into three‐dimensional framework structures, using different combinations of N—H…N, N—H…O, C—H…O, C—H…N and C—H…π hydrogen bonds in each case. Oxidative cleavage of 6‐methoxy‐N⁵‐(4‐methylbenzyl)‐4‐[2‐(4‐methylphenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidine‐2,5‐diamine, (II), with diiodine gave 6‐methoxy‐4‐[2‐(4‐methylphenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidine‐2,5‐diamine, which crystallized as a monohydrate, C₁₉H₁₈N₆O·H₂O, (V), and reaction of (V) with trifluoroacetic acid gave two isomeric products, namely N‐{5‐amino‐6‐methoxy‐6‐[2‐(4‐methylphenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidin‐2‐yl}‐2,2,2‐trifluoroacetamide, which crystallized as an ethyl acetate monosolvate, C₂₁H₁₇F₃N₆O₂·C₄H₈O₂, (VI), and N‐{2‐amino‐6‐methoxy‐4‐[2‐(4‐methylphenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidin‐5‐yl}‐2,2,2‐trifluoroacetamide, which crystallized as a methanol monosolvate, C₂₁H₁₇F₃N₆O₂·CH₄O, (VIIa). For each of (V), (VI) and (VIIa), the supramolecular assembly is two‐dimensional, based on different combinations of O—H…N, N—H…O, N—H…N, C—H…O and C—H…π hydrogen bonds in each case. Comparisons are made with some related structures.     

Preparation of 2,3‐dihydro‐1H,5H‐pyrido[3,2,1‐ij]quinoline‐1,5‐dione derivatives

The 2,3‐dihydro‐7‐methyl‐1H,5H‐pyrido[3,2,1‐ij]quinoline‐1,5‐dione derivatives 9 and 10 were prepared from 3‐(5,7‐dimethoxy‐4‐methyl‐2‐oxo‐2H‐quinolin‐1‐yl)propionitrile ( 6 ). Cyclodehydration of the amide 8 gave 1,2‐dihydro‐7,9‐dimethoxy‐6‐methylpyimido[1,2‐a]quinolin‐3‐one ( 11 ).     

A simple synthesis of 4‐chloro‐5‐hydroxy‐1H‐benzo[g]indoles

The reaction of methyl 2‐(3‐chloro‐1,4‐dioxo‐1,4‐dihydronaphthalen‐2‐yl)propenoate ( 2a ) with primary amines gave 4‐chloro‐5‐hydroxy‐3‐methoxycarbonyl‐1H‐benzo[g]indoles 5a‐f as major compounds and 3‐methoxycarbonyl‐4,9‐dioxo‐2,3,4,9‐tetrahydro‐1H‐benzo[f]indoles 6a‐d as minor ones. Whereas the reaction of 3‐(3‐chloro‐1,4‐dioxo‐1,4‐dihydronaphthalen‐2‐yl)‐3‐buten‐2‐one ( 2b ) with primary amines afforded the corresponding 1H‐benzo[g]indoles 5g‐i as major products and 3‐acetyl‐4,9‐dihydro‐4,9‐dioxo‐1H‐benzo[f]indoles 7g, h as minor products.     

Synthesis of 2‐Aryl‐2,3‐dihydro‐1,8‐naphthyridin‐4(1H)‐ones by Deprotective Cyclization of N‐{3‐[(2E)‐3‐Arylprop‐2‐enoyl]pyridin‐2‐yl}‐2,2‐dimethylpropanamides in Water

A new and convenient method for the preparation of 2‐aryl‐2,3‐dihydro‐1,8‐naphthyridin‐4(1H)‐ones 4 has been developed. Thus, N‐{3‐[(2E)‐3‐arylprop‐2‐enoyl]pyridin‐2‐yl}‐2,2‐dimethylpropanamides 3 are synthesized from commercially available pyridin‐2‐amine using an easily performed three‐step sequence and are subjected to cyclization with deprotection under acidic conditions in H₂O to give the desired products. Similarly, 2‐aryl‐2,3‐dihydro‐1,7‐naphthyridin‐4(1H)‐ones 8 and 2‐aryl‐2,3‐dihydro‐1,6‐naphthyridin‐4(1H)‐ones 12 can be prepared from pyridin‐3‐amine and pyridin‐4‐amine, respectively.     

Syntheses of N‐[3‐(1‐methyl‐1H‐2‐imidazolyl)propyl]benzamides and N‐[3‐(1‐methyl‐1H‐2‐imidazolyl)propyl]benzenesulfonamides

A series of substituted N‐(4‐substituted‐benzoyl)‐N‐[3‐(1‐methyl‐1H‐imidazol‐2‐yl)propyl]amines ( 13 ) and N‐arylsulfonyl‐N‐[3‐(1‐methyl‐1H‐imidazol‐2‐yl)propyl]amines ( 14 ) were prepared from the reaction of 3‐(1‐methyl‐1H‐imidazol‐2‐yl)propan‐1‐amine ( 7 ) with substituted benzoyl chloride or substituted‐benzene sulfonyl chloride respectively. Compound 7 was prepared by two independent methods.     

Attempted synthesis of ethyl 3,4‐dihydro‐2H‐1,4‐benzoxazine‐3‐carboxylate and 3‐acetate derivatives

Ethyl 3,4‐dihydro‐2H‐1,4‐benzoxazine‐3‐carboxylate derivatives 2 were obtained and isolated in low yields from the condensation of 2‐aminophenol and ethyl 2,3‐dibromopropanoate. They can be obtained by hydrogenation of ethyl 2H‐1,4‐benzoxazine‐3‐carboxylate in satisfactory yield. Using 2‐iminophenol did not direct the condensation with ethyl 2,3‐dibromopropanoate towards 2 but was fruitfull for the preparation of ethyl 2‐(4‐benzyl‐3,4‐dihydro‐2H‐1,4‐benzoxazin‐3‐yl)acetate from ethyl bromocrotonate.     

Bases,solvates and salts: new benzimidazole‐ and pyridine‐scaffolded ligands

The intermolecular interactions in the structures of a series of Schiff base ligands have been thoroughly studied. These ligands can be obtained in different forms, namely, as the free base 2‐[(2E)‐2‐(1H‐imidazol‐4‐ylmethylidene)‐1‐methylhydrazinyl]pyridine, C₁₀H₁₁N₅, 1 , the hydrates 2‐[(2E)‐2‐(1H‐imidazol‐2‐ylmethylidene)‐1‐methylhydrazinyl]‐1H‐benzimidazole monohydrate, C₁₂H₁₂N₆·H₂O, 2 , and 2‐{(2E)‐1‐methyl‐2‐[(1‐methyl‐1H‐imidazol‐2‐yl)methylidene]hydrazinyl}‐1H‐benzimidazole 1.25‐hydrate, C₁₃H₁₄N₆·1.25H₂O, 3 , the monocationic hydrate 5‐{(1E)‐[2‐(1H‐1,3‐benzodiazol‐2‐yl)‐2‐methylhydrazinylidene]methyl}‐1H‐imidazol‐3‐ium trifluoromethanesulfonate monohydrate, C₁₂H₁₃N₆⁺·CF₃O₃S^?·H₂O, 5 , and the dicationic 2‐{(2E)‐1‐methyl‐2‐[(1H‐imidazol‐3‐ium‐2‐yl)methylidene]hydrazinyl}pyridinium bis(trifluoromethanesulfonate), C₁₀H₁₃N₅²⁺·2CF₃O₃S^?, 6 . The connection between the forms and the preferred intermolecular interactions is described and further studied by means of the calculation of the interaction energies between the neutral and charged components of the crystal structures. These studies show that, in general, the most important contribution to the stabilization energy of the crystal is provided by π–π interactions, especially between charged ligands, while the details of the crystal architecture are influenced by directional interactions, especially relatively strong hydrogen bonds. In one of the structures, a very interesting example of the nontypical F…O interaction was found and its length, 2.859 (2) Å, is one of the shortest ever reported.     

A new two‐dimensional CoII coordination polymer based on bis[4‐(2‐methyl‐1H‐imidazol‐1‐yl)phenyl] ether and biphenyl‐4,4′‐diyldicarboxylic acid: synthesis,crystal structure and photocatalytic degradation activity

A novel two‐dimensional Co^II coordination framework, namely poly[(μ₂‐biphenyl‐4,4′‐diyldicarboxylato‐κ²O⁴:O^4′){μ₂‐bis[4‐(2‐methyl‐1H‐imidazol‐1‐yl)phenyl] ether‐κ²N³:N^3′}cobalt(II)], [Co(C₁₄H₈O₄)(C₂₀H₁₈N₄O)]_n, has been prepared and characterized by IR, elemental analysis, thermal analysis and single‐crystal X‐ray diffraction. The crystal structure reveals that the compound has an achiral two‐dimensional layered structure based on opposite‐handed helical chains. In addition, it exhibits significant photocatalytic degradation activity for the degradation of methylene blue.