Synthesis,anti-inflammatory and analgesic activity of 2-[4-(substituted benzylideneamino)-5-(substituted phenoxymethyl)-4H-1,2,4-triazol-3-yl thio] acetic acid derivatives

The title compounds 3a–l have been synthesized by the reaction of thiocarbohydrazide with substituted phenoxy acetic acid to obtained substituted 1,2,4-triazoles (1). Compound 1 was treated with various substituted aromatic aldehydes which results in 4-(substituted benzylideneamino)-5-(substituted phenoxymethyl)-2H-1,2,4-triazol-3(4H)-thiones (2a–g), further 2a–g is converted to 2-[4-(substituted benzylideneamino)-5-(substituted phenoxymethyl)-4H-1,2,4-triazol-3-yl thio] acetic acid (3a–l) derivatives by the reaction with chloroacetic acid. All the newly synthesized compounds were evaluated for in vivo anti-inflammatory and analgesic activities. Among the series 2-[4-(2,4-dichlorobenzylideneamino)-5-(phenoxymethyl)-4H-1,2,4-triazol-3-yl thio] acetic acid (3d), 2-[4-(4-dichlorobenzylideneamino)-5-(phenoxymethyl)-4H-1,2,4-triazol-3-yl thio] acetic acid (3e), 2-[4-(2,4-dichlorobenzylideneamino)-5-[(2,4-dichlorophenoxy)methyl]-4H-1,2,4-triazol-3-yl thio] acetic acid (3j) and 2-[5-[(2,4-dichlorophenoxy)methyl)]-4-(4-chlorobenzylideneamino)-4H-1,2,4-triazol-3-yl thio] acetic acid (3k) showed significant anti-inflammatory activity with P < 0.001 (63.4%, 62.0%, 64.1% and 62.5% edema inhibition, respectively), as compared to the standard drug diclofenac (67.0%) after third hour respectively and also compounds 3j, 3k exhibited significant analgesic activity with P < 0.001 (55.9% and 54.9% protection, respectively) and less ulcerogenic activity as compared with standard drug aspirin (57.8%).     

Synthesis,spectroscopic studies and structures of square-planar nickel(II) and copper(II) complexes derived from 2-{(Z)-[furan-2-ylmethyl]imino]methyl}-6-methoxyphenol

Two new nickel(II) [Ni(L)₂] and copper(II) [Cu(L)₂] complexes have been synthesized with bidentate NO donor Schiff base ligand (2-{(Z)-[furan-2-ylmethyl]imino]methyl}-6-methoxyphenol) (HL) and both complexes Ni(L)₂ and Cu(L)₂ have been characterized by elemental analyses, IR, UV–vis, ¹H, ¹³C NMR, mass spectroscopy and room temperature magnetic susceptibility measurement. The tautomeric equilibria (phenol-imine, O–H?N and keto-amine, O?H–N forms) have been systemetically studied by using UV–vis absorption spectra for the ligand HL. The UV–vis spectra of this ligand HL were recorded and commented in polar, non-polar, acidic and basic media. The crystal structures of these complexes have also been determined by using X-ray crystallographic techniques. The complexes Ni(L)₂ and Cu(L)₂ crystallize in the monoclinic space group P2₁/n and P2₁/c with unit cell parameters: a = 10.4552(3) Å and 12.1667(4) Å, b = 8.0121(3) Å and 10.4792(3) Å, c = 13.9625(4) Å and 129.6616(3)Å, V = 1155.22(6) Å³ and 1155.22(6) Å³, D_x = 1.493 and 1.476 g cm^?3 and Z = 2 and 2, respectively. The crystal structures were solved by direct methods and refined by full-matrix least squares to a find R = 0.0377 and 0.0336 of for 2340 and 2402 observed reflections, respectively.     

The experimental and DFT studies of 1,3-dimethyl-2-[4-chloro-styryl]-benzimidazolium iodide

1,3-Dimethyl-2-[4-chloro-styryl]-benzimidazolium iodide (1) was synthesized and characterized by X-ray diffraction, ¹H NMR, MS, IR, UV–vis spectra and elemental analysis. The crystals are monoclinic, space group P2₁/c, with a = 12.507(3) Å, b = 7.3259(19) Å, c = 36.705(9) Å, V = 3358.9(15) Å³, and Z = 4 (at 296(2) K). Crystal stacking scheme indicates the face-to-face π?π aromatic stacking interactions. Molecular geometries, frequencies, IR, ¹H NMR and UV–vis were calculated at DFT/TD-DFT level using two hybrid exchange–correlation functionals, B3LYP and PBE1PBE. The stability of the molecule arising from hyperconjugative interaction and charge delocalization had been analyzed using natural bond orbital (NBO) analysis. These calculations on (1) provide deep insight into its electronic structure and properties.     

Synthesis of palladium–biscarbene complexes derived from 1,1′-methylenebis(1,2,4-triazole) functionalized in the methylene bridge

Palladium–biscarbene complexes derived from N,N′-bis(1,2,4-triazol-1-yl)methane, which bear an alkyl chain functionalized with a hydroxyl group, have been synthesized ([Pd(L1)Br₂] (6) and [Pd(L1)I₂] (7) [L1 = 1,1′-(3-hydroxypropylidene)bis(4-butyl-4,5-dihydro-1H-1,2,4-triazol-5-ylidene)]). Each product is obtained as a non-equimolecular mixture of two conformers. The hydroxyl group has been replaced by bromide and methanesulphonate and ( [Pd(L2)Br₂] [L2 = 1,1′-(3-bromopropylidene)bis(4-butyl-4,5-dihydro-1H-1,2,4-triazol-5-ylidene)] (9)) and ([Pd(L3)Br₂] [L3 = 1,1′-(3-methanesulphonyloxypropylidene)-bis(4-butyl-4,5-dihydro-1H-1,2,4-triazol-5-ylidene)] (10)) were obtained, respectively, as mixtures of conformers. All compounds consist of a six-membered metallacyclic structure in a boat conformation. Major conformers present the functionalized chain in the axial position, while in minor conformers it is located in the equatorial position.     

Synthesis and characterization of novel intramolecularly O,C,O-coordinated heteroleptic organostannylenes and their tungstenpentacarbonyl complexes

The syntheses are reported of the novel heteroleptic organostannylenes [2,6-(ROCH₂)₂C₆H₃]SnCl (1, R = Me; 2, R = t-Bu) and of their tungstenpentacarbonyl complexes [2,6-(ROCH₂)₂C₆H₃](X)SnW(CO)₅ (3, X = Cl, R = Me; 4, X = Cl, R = t-Bu; 5, X = H, R = Me). The compounds were characterized by means of elemental analyses, ¹H, ¹³C, ¹¹⁹Sn NMR spectroscopies, electrospray mass spectrometry and in case of 3 and 4 also by single crystal X-ray diffraction analysis. For the two latter compounds the substituents bound at the ether oxygen atom control the strength of intramolecular O → Sn coordination. Thus, the O–Sn distances amount to 2.391(5)/2.389(5) (3) and 2.464(3)/2.513(3) Å (4).     

Synthesis of some Mannich base derivatives and their antimicrobial activity study

A series of 2-(phenyl)-2-(morpholin-4-yl)-N-phenylacetamide I–VII were synthesized by Mannich base method. Synthesized compounds I–VII were confirmed by IR, ¹H NMR, ¹³C NMR, mass and elemental analyses. Synthesized compounds I–VII were screened for antibacterial activity against various bacterial strains and compared with standard Ciprofloxacin at concentration 100 μg/mL and for antifungal activity against various fungal strains and compared with Clotrimazole at concentration 100 μg/mL; particularly 3-(4-chlorophenyl)-3-(morp holin-4-yl)-N-phenylpropanamide lll that has high antibacterial activity against Streptococcus epidermidis was compared with standard Ciprofloxacin.     

Synthesis,characterization and catalytic behaviors of neutral nickel complexes: Arylnickel N-alkyl-6-(1-(arylimino)ethyl)picolinamide

A series of novel neutral nickel complexes, aryl (phenyl or naphthyl) nickel N-alkyl-6-(1-(arylimino)ethyl)picolinamides, were synthesized and characterized by NMR and IR spectroscopy and elemental analysis. Single-crystal X-ray diffraction analyses of the complexes C2, C3 and C7 reveal distorted square-planar geometry along with the molecular structure of one free ligand L1. On activation with diethylaluminum chloride (Et₂AlCl), the nickel complexes exhibited moderate catalytic activities for ethylene oligomerization, and the catalytic activity was up to 2.45 × 10⁵ g mol^?1(Ni) h^?1 in the presence of 1 equiv. PPh₃. Moreover, these complexes also exhibit moderate activities for Kumada–Corriu reaction and polymerization of methyl methacrylate.     

Synthesis and structural study of (8-phenylsulfanylnaphth-1-yl)diphenylphosphine metal complexes

A series of three platinum(II) halide complexes 2–4 [Pt(X)₂{Nap(PPh₂)(SPh)}] (Nap = naphthalene-1,8-diyl; X = Cl, Br, I) and a ruthenium(II) p-cymene complex 5 [Ru(η⁶-MeC₆H₄ⁱPr)(Cl){Nap(PPh₂)(SPh)}]⁺Cl^? of the sterically crowded peri-substituted naphthalene phosphine 1 have been prepared. The compounds were fully characterised by multinuclear NMR, IR and MS and X-ray data for 1–5 are compared. Molecular structures are analysed by naphthalene ring torsions, peri-atom displacement, splay angle magnitude, P···S interactions, aromatic ring orientations and geometry around the metal centre. Platinum adopts a strictly square planar geometry which increases the distortion of the naphthalene skeleton in 2–4. Conversely, the classical-piano stool conformation of 5 results in a pseudo-octahedral conformation around the ruthenium atom which influences the naphthalene geometry to a much lesser extent with distortion of a similar magnitude to the free ligand 1.     

Novel N-substituted-5-phenyl-1H-pyrazole-4-ethyl carboxylates as potential NLO materials

In the present investigation we have synthesized a novel series of N-substituted-5-phenyl-1H-pyrazole-4-ethyl carboxylates, which are characterized by ¹H NMR, UV–Vis and FT-IR spectroscopy methods. The optical nonlinearity of the compounds in chloroform solution has been studied at 532 nm using 5 ns laser pulses, employing the open-aperture z-scan technique. It is found that compound 3c having carboxylic acid group and ester substituent has maximum nonlinearity. From measurements we conclude that compounds 3c (4-[4-(ethoxycarbonyl)-5-phenyl-1H-pyrazol-1-yl]benzoic acid) and 3e (ethyl 1-(2-bromophenyl)-5-phenyl-1H-pyrazole-4-carboxylate) are potential candidates for optical limiting applications.     

Synthesis and reactions of heterodinuclear organopalladium–cobalt complexes acting as copolymerization catalyst for aziridine and carbon monoxide

A series of heterodinuclear acylpalladium–cobalt complexes having a bidentate nitrogen ligand, L₂(RCO)Pd–Co(CO)₄ (L₂ = bpy, R = Me (5), Ph (6); L₂ = tmeda, R = Me (7), Ph (8); L₂ = phen, R = Me (9), Ph (10)) are prepared by metathetical reactions of PdRIL₂ with Na⁺[Co(CO)₄]⁻ followed by treatment with CO. These complexes are characterized by NMR and IR spectroscopies and elemental analyses, and the molecular structures of 6, 8, and 9 are determined by X-ray structure analysis. Geometry at Pd is essentially square planar and the Co atom is considered to have d¹⁰ tetrahedral structure, where cobalt(-I) anion coordinates to palladium(II) cation. Heterodinuclear organopalladium–cobalt complexes are shown to catalyze copolymerization of aziridines and CO under mild conditions. Reaction of (dppe)MePd–Co(CO)₄ (1) with aziridine gives a cationic (aziridine)palladium(II) complex with [Co(CO)₄]⁻ anion, [PdMe(aziridine)(dppe)]⁺[Co(CO)₄]⁻ (13).     

Approaches to (R)- and (S)-1′-(1-aminoethyl)ferrocene-1-carboxylic acid derivatives

Lipase-catalyzed esterification of (±)-methyl 1′-(1-hydroxyethyl)ferrocene-1-carboxylate 4 afforded its (R)-acetate (−)-5 (ee = 99%) and (S)-(+)-4 (ee = 90%). Stereoretentive azidation/amination/acetylation of (R)-(−)-5 gave (R)-(+)-methyl 1′-(1-acetamidoethyl)ferrocene-1-carboxylate (R)-3 (ee = 98%). In a similar manner (S)-(+)-4 was converted into (S)-(−)-3 (ee = 84%). Both enantiomers of 3 were obtained in high chemical yields without a loss of enantiomeric purity. The title compounds can be coupled with natural amino acids and peptides on both C- and N-termini.     

DNA binding,docking studies,artificial nuclease activity and in vitro cytotoxicity of newly synthesized steroidal 1H–pyrimidines

A new series of steroidal pyrimidines (7–9) has been synthesized by reacting steroidal thiosemicarbazones (4–6) with ethyl cyanoacetate. The compounds were characterized by IR, ¹H NMR, ¹³C NMR, MS and analytical data. The interaction studies of compounds 7–9 with DNA were carried out by UV–vis and luminescence spectroscopy. Compounds (7–9) bind to DNA preferentially through electrostatic and hydrophobic interactions, with K_b values found to be 6.56 × 10³ M⁻¹, 1.54 × 10⁴ M⁻¹ and 9.34 × 10³ M⁻¹, respectively, indicating the higher binding affinity of compound 8 towards DNA. Gel electrophoresis pattern demonstrated that compound 8 shows strong interaction with DNA and that, during its cleavage activity with pBR322 DNA, it seems to follow the mechanistic pathway involving the generation of singlet oxygen and a superoxide anion, which are responsible for initiating DNA strand scission. The docking study suggested that the intercalation of compounds in between the nucleotide base pairs is due to the presence of a pyrimidine moiety in the steroid molecule. MTT assay was carried out to check the toxicity of new compounds 7–9 against the different human cancer as well as non-cancer cell lines A545, MCF-7, HeLa, HL-60, SW480, HepG2, HT-29, A549, 184B5, MCF10A, NL-20, HPC, and HPLF. Apoptotic degradation of DNA in the presence of steroidal pyrimidines 7–9 was analysed by agarose gel electrophoresis and visualized by ethidium bromide staining (comet assay).     

Synthesis and characterization of novel five-membered palladacycles

3-(2-Chloroquinolin-3-yl)-1,5-bis(3,4,5-trimethoxy-phenyl)-pentane-2,4-dione derivatives 3a–b were conveniently synthesized in excellent yields (82% each) by tandem Knoevenagel condensation reactions of 2-chloro-3-carbaldehyde-quinoline 1a–b with 3,4,5-trimethoxy acetophenone, followed by a base catalyzed Michael addition, such as DBU (1,8-diazabicyclo[5,4,0]undec-7-ene) with or without solvent. The reactions of 3a–b with Pd(dba)₂ in the presence of PPh₃ (1:2) in degassed acetone provided the dinuclear palladium complexes {Pd(C,N-2-C₉H₄N–CH–[–CH₂CO(3,4,5-(OMe-)₃–C₆H₂-]₂–3-R-6)Cl(PPh₃)}₂ [(R = H (4a), R = OMe (4b)] in moderate yields (38% and 43%), which in turn reacted with an excess of isonitrile XyNC (Xy = 2,6-Me₂C₆H₃) to give the corresponding palladacycles 5a–b in moderate yields (45% and 43%). The palladacycles 5a–b were also obtained in similar yields (32% and 33%) via a one-pot oxidative addition reaction of 3a-b with isonitrile XyNC:Pd(dba)₂ (4:1). The products were characterized by satisfactory elemental analysis and spectral studies (IR, ¹H, and ³¹P NMR). The crystal structure of 5a was determined by X-ray crystallography diffraction studies.     

Coordination asymmetry in μ-oxido divanadium complexes: Development of synthetic protocols

This brief review deals with the development of a general protocol for the synthesis of μ-oxido divanadium(V) compounds [LOV^V-(μ-O)-V^VO(Salen)] (L = L¹–L⁵) (1–5) incorporating coordination asymmetry. One of the vanadium centers in these compounds has an octahedral environment, completed by tetradentate Salen ligand, while the other center has a square pyramidal geometry, made up of tridentate biprotic Schiff-base ligands (H₂L^1–5) with ONO (1–3) and ONS (4, 5) type donor combinations. Single crystal X-ray diffraction, ESI-MS, and multi-nuclear NMR (¹H and ⁵¹V) spectroscopy have been used extensively for the characterization of these compounds. The V₂O₃ core in these compounds, save 3, has a rare type of twist-angular structure. The V(1)?V(2) separations (3.7921(7)–3.3084(6) Å) are by far the largest in these compounds compared to their peers containing a V₂O₃ core. The molecules retain their unsymmetrical binuclear structures also in solution as established by NMR spectroscopy. The mixed-oxidation compound (ImH)[L⁴OV^IV-(μ-O)-V^VOL⁵] 7 containing two dissimilar ligands has a V₂O₃ core with a syn-angular structure and exhibits crystallographically imposed mirror symmetry due to static disorder. In solution of donor solvents, this angular core structure changes into a linear one (anti-linear) by accepting solvents in to the vacant coordination site of the metal centers. Finally, the protocol for the synthesis of heterobimetallic compounds with vanadium(V) and Re(VII) combination flanked by a single μ-oxido bridge has been developed in which the precursor complexes [V^IVOL^6,7] (H₂L^6,7 are Salen type of ligands) are allowed to oxidize aerially in the presence of added perrhenate anion. The oxidized [V^VOL^6,7]⁺ species hold the ReO₄^? anion in the vacant coordination site of the metal ion, trans to the terminal oxido group, thus generating the V^V–O–Re^VII moiety in the heterobimetallic compounds (9 and 10). Both X-ray crystallography and ¹H NMR spectroscopy have been used to establish the identities of these compounds. In compound 9, the Re(1)–O(11)–V(1) bridge angle is barely linear (170.2(3)°) with a Re?V separation of 3.9647(9) Å. The redox behavior of 9 and 10 are quite interesting, each undergoing two reductions both in the positive potential range at E_1/2 = 0.59 and 0.16 V vs. Ag/AgCl reference and have single-electron stoichiometry, confirmed by constant potential coulometry.     

Ultrasound-assisted,one-pot,three-component synthesis and antibacterial activities of novel indole derivatives containing 1,3,4-oxadiazole and 1,2,4-triazole moieties

Thirteen novel indole derivatives were efficiently synthesized through ultrasound irradiation by using 4-amino-5-(1H-indol-3-yl)-4H-[1,2,4]triazole-3-thiol (8) and 2-mercapto-5-substituted-1,3,4-oxadiazoles (5a–m). Compared with conventional and microwave methods, yields increased to 82–93%, and reaction times decreased to 15–35 min. The structures of these novel compounds were characterized by spectral data and elemental analysis. Two out of the synthesized compounds (10f and 10l) exhibited excellent activity against Staphylococcus aureus and Escherichia coli, and thus warrant further research.     

Hemilability of 2-(1H-imidazol-2-yl)pyridine and 2-(oxazol-2-yl)pyridine ligands: Imidazole and oxazole ring Lewis basicity,Ni(II)/Pd(II) complex structures and spectra

Fourteen new organic molecules A1–A4, B1–B5, C1–C4 and D and a series of transition metal(II) complexes (Ni1–Ni9 and Pd1–Pd2b) were synthesized and studied in order to characterize the hemilability of 2-(1H-imidazol-2-yl)pyridine and 2-(oxazol-2-yl)pyridine ligands (A1–A4 = 2-R²-6-(4,5-diphenyl-1R¹-imidazol-2-yl)pyridines, R¹ = H or CH₃, R² = H or CH₃; B1–B5 = 1-R²-2-(pyridin-2-yl)-1R¹-phenanthro[9,10-d]imidazoles/oxazoles, R¹ = H or CH₃, R² = H or CH₃; C1–C4 = 2-(6-R²-pyridin-2-yl)-1H-imidazo/oxazo[4,5-f][1,10]phenanthrolines, R² = H or CH₃; D = 2-mesityl-1H-imidazo[4,5-f][1,10]phenanthroline). They were also used to study the substituent effects on the donor strengths as well as the coordination chemistries of the imidazole/oxazole fragments of the hemilabile ligands.All the observed protonation–deprotonation processes found within pH 1–14 media pertain to the imidazole or oxazole rings rather than the pyridyl Lewis bases. The donor characteristics of the imidazole/oxazole ring can be estimated by spectroscopic methods regardless of the presence of other strong N donor fragments. The oxazoles possessed notably lower donor strengths than the imidazoles. The electron-withdrawing influence and capacity to hinder the azole base donor strength of 4,5-azole substituents were found to be in the order phenanthrenyl (B series) > 4,5-diphenyl (A series) > phenanthrolinyl (C series). An X-ray structure of Ni5b gave evidence for solvent induced ligand reconstitution while the structure of Pd2b provided evidence for solvent induced metal–ligand bond disconnection.Interestingly, alkylation of 1H-imidazoles did not necessarily produce the anticipated push of electron density to the donor nitrogen. Furthermore, substituents on the 4,5-carbons of the azole ring were more important for tuning donor strength of the azole base. DFT calculations were employed to investigate the observed trends. It is believed that the information provided on substituent effects and trends in this family of ligands will be useful in the rational design and synthesis of desired azole-containing chelate ligands, tuning of donor properties and application of this family of ligands in inorganic architectural designs, template-directed coordination polymer preparations, mixed-ligand inorganic self-assemblies, etc.     

Anticancer and antimicrobial evaluation of newly synthesized steroidal 5,6 fused benzothiazines

A series of new 5α-cholestano [5,6-b] benzothiazines (4–6) has been synthesized by the reaction of 5α-cholestan-6-one (1–3) with 2-aminothiophenol in the presence of iodine. The structures of newly synthesized compounds have been established on the basis of spectral and analytical data. Compounds (1–6) were screened for in vitro anticancer activity against the human cancer cell lines; SW480 (colon adenocarcinoma cells), A549 (lung carcinoma cells), HepG2 (hepatic carcinoma cells) and HeLa (cervical cancer cells) using MTT assay during which the products (4–6) showed marked increase in anticancer activity and in particular, compound 6 showed IC₅₀ = 13.73 μmol L⁻¹ against HeLa cells, being more effective than Doxorubicin against the same cells. Compounds 4 and 6 also showed minimum IC₅₀ of 15.83 μmol L⁻¹ and 16.89 μmol L⁻¹ against HepG2 and A549 cells, respectively. Compounds (1–6) were also tested for in vitro antimicrobial activity against different bacterial as well as fungal strains during which newly synthesized compounds (4–6) were found more potent than starting compounds (1–3). Compound 4 was found to be more potent than the reference drug, Chloramphenicol, in the case of Escherichia coli while compound 5 was found almost equally potential antifungal agent against P. marneffei in comparison with the reference drug, Nystatin.     

Diazenyl schiff bases: Synthesis,spectral analysis,antimicrobial studies and cytotoxic activity on human colorectal carcinoma cell line (HCT-116)

A series of diazenyl schiff bases have been synthesized by reaction of salicylaldehyde containing azo dyes with various substituted aniline derivatives in the presence of acetic acid as catalyst. The structures of diazenyl derivatives were determined by FTIR, UV–vis, ¹H NMR, ¹³C NMR, CHN analysis, fluorimetric and mass spectroscopic studies. The synthesized derivatives were screened for their in vitro antimicrobial activity against various Gram-positive (S. aureus, B. subtilis, B. cereus), Gram-negative (S. typhi, S. enterica, E. coli, P. aeruginosa) bacterial and fungal (C. albicans, A. niger and A. fumigatus) strains, using cefadroxil (antibacterial) and fluconazole (antifungal) as standard drugs. The diazenyl schiff bases were also screened for their cytotoxicity against human colorectal carcinoma cell line (HCT-116) using 5-fluorouracil as standard drug by Sulforhodamine-B Stain (SRB) assay. The schiff bases exhibited significant activity toward both Gram-positive, Gram-negative bacterial and fungal strains. Most of the synthesized derivatives showed high activity against S. enterica. 4-((2,5-Dichlorophenyl)diazenyl)-2-((3-bromophenylimino)methyl)phenol (SBN-40) was found to be very active against S. aureus, B. cereus and E. coli, with MIC = 0.69 (µM/ml × 10²). The compound 4-((2-bromophenyl)diazenyl)-2-((4-nitrophenylimino)methyl)phenol (SBN-13) possessed comparable activity (IC₅₀ = 7.5 µg/ml) to the standard drug 5-fluorouracil (IC₅₀ = 3.0 µg/ml) against human colorectal carcinoma cell line (HCT-116).     

Synthesis of new substituted benzaldazine derivatives,hydrogen bonding-induced supramolecular structures and luminescent properties

Syntheses of three benzaldazine compounds 1–3 with the general formula Ar₁(CH = N–N = HC)Ar₂ (Ar₁ = Ar₂ = 2-OH-3,5-^tBu₂C₆H₂ (1), Ar₁ = Ar₂ = 2-BrC₆H₄ (2), Ar₁ = ortho-C₆H₄(NHC₆H₃-Me₂-2,6), Ar₂ = C₆H₄F-2 (3)) are described. All compounds were characterized by elemental analysis, ¹H NMR, ¹³C NMR, IR spectroscopy and single-crystal X-ray crystallography. The different supramolecular structures were obtained through different weak interactions (C ? H···O, O ? H···N and π···π interactions for 1; C ? H···Br and Br···Br interactions for 2; C ? H···F and C ? H···N interactions for 3). Compound 1 shows solvent-dependent fluorescent properties with blue to green emission on the increasing of the solvent polarity. Compounds 2, 3 show blue photoluminescence in different solvents.     

Dinuclear Rh(I) complex with 2,7-bis(diphenylphosphino)-1,8-naphthyridine: Synthesis,structure, and dynamic property

Reaction of [RhCl(cod)]₂ with 2,7-bis(diphenylphosphino)-1,8-naphthyridine (dpnapy) and 2,6-xylyl isocyanide (XylNC) in the presence of NH₄PF₆ afforded the dirhodium(I) complex, [Rh₂(μ-dpnapy)₂(XylNC)₄](PF₆)₂ (5), and similar procedures using [MCl₂(cod)] (M = Pt, Pd) resulted in the formation of [Pt₂(μ-dpnapy)₂(XylNC)₄](PF₆)₄ (6) and [Pd₂Cl₂(μ-dpnapy)₂(XylNC)₂](PF₆)₂ (7). Complexes 5–7 were characterized by elemental analysis, IR, UV–Vis, ¹H and ³¹P{¹H} NMR, and ESI mass spectroscopic techniques, to involve a small and rigid d⁸ {M₂(μ-dpnapy)₂} metallomacrocycle. Complex 5 readily incorporated a silver(I) ion into the macrocycle to afford [Rh₂Ag(μ-dpnapy)₂(XylNC)₄](PF₆)₃ (8) which was characterized by X-ray crystallography. The Ag(I) ion is trapped by two trans N atoms of dpnapy ligands, resulting in an asymmetric Rh–Ag⋯Rh structure, determined as a disordered model in the crystal structure, and however, in a CH₂Cl₂ solution, a dynamic interconversion of the two Ag-trapped sites was observed with low-temperature NMR studies, which was further supported by DFT molecular orbital calculations. When an acetonitrile solution of complex 5 was treated over a droplet of mercury(0), the polymeric compound formulated as {[Rh(μ-dpnapy)(XylNC)₂](PF₆)}_n (9) was isolated as yellow single crystals, which were revealed by X-ray crystallography to consist of C₆ helical rods along c axis with a pitch of 33.5 Å (rise of unit = 5.6 Å) and a diameter of 20.64 Å.