Recognition of anions and monocarboxylic acids by a fluorescent guanidine-based receptor

A guanidine-based fluorescent receptor has been synthesised to study its binding behaviour towards anions (F^? , Cl^? , Br^? , I^?  and AcO^? ). The two donor N–H bonds of the receptor do not point in the same direction; rather, one N–H bond is intramolecularly hydrogen-bonded with the carbonyl oxygen atom. The nature of the donor–acceptor (DA) arrangement induces moderate binding properties. The binding behaviour towards monocarboxylic acids (benzoic acid and phenylacetic acid) is also compared. The binding behaviour of receptor 1 towards the F^?  anion is higher among the anions studied, whereas in the case of monocarboxylic acid, the binding constant with phenylacetic acid is higher than benzoic acid.     

Crystal Structure Investigations of Inclusion Complexes Between β-cyclodextrin and Alkyl(aqua)cobaloximes (Alkyl=Butyl,Hexyl and Cyclohexyl)

The crystal and molecular structures of alkylcobaloxime/ g -cyclodextrin ( g -CD) inclusion complexes: butyl(aqua)cobaloxime/ g -CD ( 1 ). hexyl(aqua)cobaloxime/ g -CD ( 2 ) and cyclohexyl(aqua)cobaloxime/ g -CD ( 3 ) were determined by X-ray diffraction analyses. Crystal data for 1 14H 2 O: P 2 1 2 1 2 1 , a =15.1335(3), b =18.9630(2), c =28.1545(5) Å, Z =4; 2 12H 2 O: P 2 1 2 1 2 1 , a =15.1135(4), b =19.1477(5), c =28.2715(7) Å, Z =4; 3 10H 2 O: P 2 1 2 1 2 1 , a =15.6898(2), b =16.9094(2), c =28.9762(2) Å, Z =4. The structural and conformational comparisons for the three g -CD inclusion complexes with their guest molecules as well as other CD inclusion analogs are discussed.     

具有梯形结构钴(Ⅱ)配位聚合物的合成及晶体结构

Co(NO₃)₂, N-carbazolyacetic acid and 4,4′-bipyridyl can give rise to a novel coordination polymer [CO₂(Cabo)₂(NO₃)₂(4,4′-bipy)₂]_n using a fritted U-tube. Single crystal X-ray diffraction displays in the complex, each Co(Ⅱ) is six-coordinated by two N atoms from different 4,4′-bipyridyl ligands, two O atoms of the bridge from two N-carbazolyacetic acid and two O atoms of one nitrate anion to form a distorted octahedral. Two O atoms of the carboxyl group act as bridge to link two Co(Ⅱ) atoms. The resulting structure is a ladder polymer. CCDC: 211713.     

A comparative study on structure and conformation of three hydroxybenzylamine ligands

Structure and conformation of three tridentate ligands are determined. All these three compounds crystallize in different space groups, the details are as follows: Bis[(3,5-dimethyl,2-hydroxy)-2-hydroxy-5-methoxy]benzylcyclohexylamine (DHBC): monoclinic I2/a (a = 17.691(1) Å, b = 9.707(1) Å, c = 24.235(2) Å, = 91.028(1)°); bis[(3,5-dimethyl,2-hydroxy)-2-hydroxy-5-bromo]benzylcyclohexylamine (DHBrBC): tetragonal P4₁2₁2 (a = b = 12.1138(1) Å, c = 28.485(1) Å) and bis[(3,5-dimethyl,2-hydroxy)-2-hydroxy-5-bromo]benzylmethylamine (DHBrBM): triclinic (a = 5.228(1), b = 12.364(1) Å, c = 13.234(1) Å, = 94.04(1)°, = 95.72(1),° = 95.90(1)°). The cyclohexane rings in DHBC and DHBrBC assume chair conformation. Both the phenyl rings are planar in all the molecules and orient at angles of 75.5(1)°, 62.2(1)°, and 53.9(2)°, respectively with each other. The bond angles around N atom show the sp³ character. Inter- and intramolecular O–HN and O–HO types of hydrogen bondings stabilize the molecules in the unit cell in addition to van der Waals forces.     

一个新的双核双(μ-氧桥)锰(Ⅲ/Ⅳ)配合物的合成、结构和性质

二价锰盐和1,4,8,11－环十四四氮烷（cyclam)在溶液中自组装生成核双（μ-氧桥）锰（Ⅲ/Ⅳ）配合物;[(cyclam)MnO]2(ClO4)2(NO3)。该配合物被晶体结构表征,低温EPR表明其具有16条Mn（Ⅲ）Mn（Ⅳ）二聚体的特征信号。磁性研究确认有强的反铁磁性,J／k=-680K,g=2.0／     

Synthesis of [MoOS3Cu3I(3, 5-diMePy)4]·CH3CN and (Et4>N)4[Mo4Cu8O4S12{(Ph2PS)2N}4] from Solid State Product [Et<

Treatment of iodide bridged dimer [NEt₄]₄[Mo₂O₂S₆Cu₆I₄Br₂] 1 with 3,5-bimethylpyridine or with Kin CH₃CN afforded the tetranuclear cluster [MoOS₃Cu₃I(3,5-diMePy)₄]·CH₃CN 2 and dodecanuclear cluster (Et₄N)₄[Mo₄Cu₈O₄S₁₂{(Ph₂PS)₂N}₄] 3. Monomeric 2 possess a nest shaped skeleton. The structure of oligomeric 3 can be regarded as a tetramer of nest shaped MoCu₃OS₃ groups co polymerized by sharing the limbic Cu atoms.     

Unambiguous cis-coordination of mono- and bi-dentate Lewis bases to Ni(SN)2 Schiff-base complexes derived from S-alkyl dithiocarbazate

The bidentate Schiff-base ligand, HL¹, prepared by condensation of equivalent molar amount of o-nitrobenzaldehyde with S-benzyl dithiocarbazate, yielded the neutral square-planar complex, NiL¹₂ (1) in the presence of Ni(OAc)₂·4H₂O. Addition of pyridine to (1) and phenanthroline (phen) to NiL (3) afforded the adducts NiL¹₂(py)₂·1.5H₂O (2) and NiL(phen) (4), respectively, where H₂L is a known quadridentate (NS)₂ ligand. Single crystal X-ray analysis of (2) and (4) showed that the pyridine rings and phen occupy cis-positions in the octahedral adducts. In both cases, one N–Ni bond in the parent Ni(NS)₂ complexes is severely perturbed, thus facilitating cis-addition of the Lewis bases. The present results together with those reported previously show that cis-addition is preferred in the addition reaction of Ni(NS)₂ Schiff-base complexes derived from S-alkyl dithiocarbazate. Addition of pyridine and 2,2′-bipyridine to NiL (3) is also discussed.     

Sodium Cyanoborohydride–Mediated Direct Conversion of Some Heterocyclic Aldehydes to Esters

An exceptional oxidizing behavior of sodium cyanoborohydride is observed where electron-withdrawing heterocyclic aldehydes are directly converted to their corresponding esters on treatment of sodium cyanoborohydride in methanol. The spectral analysis and single-crystal structure confirm the formation of esters.

A case study of solid state inhibition lock opening of pyridine N-oxide in dicarboxylic acid recognition

An ethylene-linked mixed pyridine diamide receptor 1 is synthesised to study the binding with dicarboxylic acid in solid phase. In ¹H NMR, the amide proton adjacent to pyridine N-oxide shows almost negligible shift, which suggests the non-participation of the amide proton for acid binding in solution. However, in solid phase (X-ray, IR), we have found significant role of this amide proton in binding.     

Synthesis,crystal structure and nonlinear optical properties of a new cluster complex: WCu3OS3(PPh3)3{S2P(OPr i 2)2}

A new cluster compound WCu₃OS₃(PPh₃)₃{S₂P(OPr ⁱ ₂)₂}, prepared by reacting (NH₄)₂WOS₃ with PPh₃ and [CuS₂P(OPr ⁱ ₂)₂], was characterized by elemental analysis, i.r. spectroscopy and X-ray crystallography. The structure consists of a tetra-nuclear distorted tetragonal core with one W atom coordinated by one O atom, three ₃-S and three Cu atoms. Anisotropic refinement for all nonhydrogen atoms yielded the value R = 0.0718. Investigation of third-order optical nonlinearity using the Z-scan technique shows that the cluster compound exhibits good nonlinear properties with ₂ values of 1.23 × 10^–10 m w^–1 and n ₂ values of –9.3 × 10^–18 m² w^–1 respectively.