The role of hydrogen bonds in thermodynamic and structural properties in binary mixtures of morpholine + 2-methylcyclohexanol: a combined experimental and computational study

Structural Chemistry - Thermodynamic properties of binary mixtures of 2-methylcyclohexanol with morpholine are measured as a function of composition and temperature. The excess molar volumes were...     

A novel inorganic–organic nanohybrid material SBA-15@triazine/H<Subscript>5</Subscript>PW<Subscript>10</Subscript>V<Subscript>2</Subscript>O<Subscript>40</Subscript> as efficient catalyst for the one-pot multicomponent synthesis of multisubstituted pyridines

A novel inorganic–organic nanohybrid material SBA-15@triazine/H₅PW₁₀V₂O₄₀ (SBA-15@ADMPT/H₅PW₁₀V₂O₄₀) was prepared and used as an efficient, eco-friendly, and highly recyclable catalyst for the one-pot multicomponent synthesis of multisubstituted pyridines from the reaction of aldehydes, cyclic ketones, malononitrile, and ammonium acetate with good to excellent yields (77–97%). The nanohybrid catalyst was prepared by the chemical anchoring of Keggin heteropolyacid H₅PW₁₀V₂O₄₀ onto the surface of SBA-15 mesoporous silica modified with 2-APTS -4,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)-1,3,5-triazine (ADMPT) linker. Standard characterization data such as FT-IR, XRD, SEM, TEM, BET, EDX, and DTA-TGA spectroscopy confirmed that the heteropolyacid H₅PW₁₀V₂O₄₀ is well dispersed on the surface of the solid support and its structure is preserved after immobilization on the SBA-15 mesoporous silica modified with ADMPT. Furthermore, the nanocatalyst can be recovered easily and reused five times without considerable loss of catalytic activity. In general, these advantages highlight this protocol as an attractive and useful methodology, among the other methods reported in the literature, for the eco-friendly and rapid synthesis of biologically active multisubstituted pyridines.     

Insertion of tin(II) bromide into Pt–X (X = Cl,Br) bond of dimethylplatinum(IV) complexes: A novel polymorphic form of [PtBr2(bpy)]

The platinum(II) complex [PtMe₂(bpy)] (bpy = 2,2′-bipyridine) reacted with a large excess of dihaloalkanes X(CH₂)_nX (n = 1, X = Cl; n = 4, X = Br) to form the platinum(IV) complexes [PtMe₂X{(CH₂)_nX}(bpy)] (n = 1, X = Cl, 1a; n = 4, X = Br, 1b). The reaction of complexes 1a and 1b with SnBr₂ resulted in insertion of SnBr₂ into Pt–X (X = Cl, Br) bond to afford the trihalostannyl complexes [PtMe₂(SnBr₂X){(CH₂)_nX}(bpy)] (n = 1, X = Cl, 2a; n = 4, X = Br, 2b). The synthesis of such trihalostannylplatinum(IV) complexes is reported for the first time. The complex 2a was decomposed in CH₂Cl₂ solution and single crystals of [PtBr₂(bpy)] (3a) were obtained. The X-ray structure determination of 3a revealed a new polymorphic form of [PtBr₂(bpy)]. The molecules undergo a remarkable stacking along the b-axis to form a zigzag Pt?Pt?Pt chain containing both short (3.799 Å) and long (5.175 Å) Pt?Pt separations through the crystal. The crystal structure is compared to that of the yellow modification of [PtBr₂(bpy)].     

高有机可溶性聚酰胺负载磷钨酸(PW_(12)/PA):合成1,3,5-三芳基-2-吡唑啉衍生物的高效催化剂(英文)

A novel compound constructed from polyoxometalate (H3PW12O40,PW12) and poly(amidoamine) (PA) was prepared at room temperature in an aqueous solution by an impregnation method.A series of novel 1,3,5-triaryl-2-pyrazoline derivatives was synthesized by the reaction between chalcone and phenylhydrazine in the presence of the title compound,PW12/PA,in high yields.The structures of the compounds obtained were determined by IR and 1H NMR spectra.     

Ab Initio Study of Conformational Properties of Heteroatom-Containing 1,2-Bisketene Analogues

Abstract

Minimum-energy and transition-state geometries of 4-oxobuta-1,3-diene-1-thione, buta-1,3-diene-1,4-dithione, 4-selenoxobuta-1,3-diene-1-thione, 4-selenoxobuta-1,3-diene-1-one, and buta-1,3-diene-1,4-diselenone were calculated using HF, B3LYP, and MP2 levels of theory and 6–31 + G* basis set by rotation around the related ?C?C? single bonds. In all of the above-mentioned molecules, the s-trans conformation was obtained as the most stable conformer with the 180° dihedral angle. In buta-1,3-diene-1,4-dithione, 4-selenoxobuta-1,3-diene-1-thione, and buta-1,3-diene-1,4-diselenone, the s-cis form of these compounds corresponded to the other energy-minimum geometry. Their skew geometries, with torsional angles approximately 100°, were a transition state for conformational interconversion between the two global minima forms. In 4-oxobuta-1,3-diene-1-thione and 4-selenoxobuta-1,3-diene-1-one, geometries with the C?C?C?C dihedral angles about 51 and 43° (respectively) were attributed to the second energy-minimum geometry. Transition-state structures from both molecules were found in the torsional angles at about 0 and 100°.

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