Self-assembly of Novel Hetero[3]rotaxane,[2]Rotaxanes and [2]Catenane

One linear template 13 and one cyclophane template 15, both incorporating two electron rich 1,4-dialkoxybenzene units and one diamide unit, have been synthesized. By utilizing donor-acceptor interaction and/or intermolecular hydrogen bonding assembling principles, one novel hetero[3]rotaxane 22·4Cl, possessing one neutral and one tetracationic ring components, has been synthesized from 13, through neutral [2]rotaxane 21 as intermediate. With 15 as template, tetracationic [2]catenane 23·4PF6 was assembled by using donor-acceptor interaction, but no neutral [2]rotaxane could be obtained under the typical conditions of hydrogen bonding assembling principle. The interlocked supramolecular compounds have been characterized and their spectral properties are investigated.     

Self－assembly of Novel Hetero[3]rotaxane, [2]Rotaxanes and [2]Catenane

One linear template 13 and one cyclophane template 15, both incorporating two electron rich 1,4‐dialkoxybenzene units and one diamide unit, have been synthesized. By utilizing donor‐acceptor interaction and/or intermolecular hydrogen bonding assembling principles, one novel hetero[3]rotazane 22·4Cl, possessing one neutral and one tetracationic ring components, has been synthesized from 13, through neutral [2]rotaxane 21 as intermediate. With 15 as template, tetracationic [2]catenane 23·4PF₆ was assembled by using donor‐acceptor interaction, but no neutral [2]rotaxane could be obtained under the typical conditions of hydrogen bonding assembling principle. The interlocked supramolecular compounds have been characterized and their spectral properties are investigated.     

Synthesis of 2-substituted 6,8-dinitro[1,2,4]triazolo[1,5-a]pyridines and the formation of the related zwitterionic σ-adducts

A method for the synthesis of 2-substituted 6,8-dinitro[1,2,4]triazolo[1,5-a]pyridines is proposed. The method includes the reaction of 2-chloro-3,5-dinitropyridine with the corresponding 5-substituted tetrazoles. The resulting compounds react with anhydro bases of α- and γ-methylazinium salts to give zwitterionic σ-adducts. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1405–1407, July, 1999.     

Studies on the Cyclisation of 4-[2′-Cyclohexenyl]-3-hydroxy[1]benzopyran-2-one

The bicyclic coumarin derivative-1, 3 propano-2-bromo-1,2-dihydro-3H-pyrano [2, 3-c] [1]benzo-pyran-5-one (8) was synthesised by a sequence of reaction viz. acetylation of 4-[2′-cyclohexenyl] -3-hydroxy [1] benzopyran-2-one (4), addition of bromine to cyclohexenyl double bond and treating the resulting acetyldi-bromo derivative (7) with 4% alcoholic KOH. Benzofuro [2, 3-c] [1] -benzopyran-6-one (10) was synthesised from 4 via oxymercuration with mercuric acetate in methanol followed by dehydrogenative damercuration with Pd-C in refluxing diphenyl ether.     

Tetraviologen calix[4]resorcine as a mediator of the electrochemical reduction of [PdCl4]2– for the production of Pd0 nanoparticles

1. Download : Download full-size image

     

The unusual stability of [NpO2Cl4]2−: Synthesis and characterisation of [NpO2(DPPMO2)2Cl]2[NpO2Cl4] and [Ph3PNH2]2[NpO2Cl4]

The [NpO₂(DPPMO₂)₂Cl][NpO₂Cl₄] complex (where DPPMO₂ = bis(diphenylphosphino)methanedioxide) contains the linear neptunyl group, {NpO₂}²⁺, with two bidentate P=O donor ligands. Coordinating anion Cl^? fills the fifth equatorial coordination site yielding a complex of general formula [NpO₂(DPPMO₂)₂X]₂[Y] (1) (where X = Cl^? and Y = [NpO₂Cl₄]^2?. Reaction between our newly prepared neptunium starting material [NpO₂Cl₂(thf)]_n and phosphinimine ligand produced crystals of [Ph₃PNH₂]₂[NpO₂Cl₄] (2). Compounds 1 and 2 have been structurally characterised.     

Enhancement of the power factor of [Bi1.68Ca2O4]RS[CoO2]1.69 – Ag composites prepared by the spray-drying method

[Bi_1.68Ca₂O₄]^RS[CoO₂]_1.69 (BCCO) sample and Ag-BCCO composites (with 10, 20 or 30 wt% Ag) have been prepared by the spray-drying technique and uniaxially/isostatically packed. Scanning electron microscopy reveals that the Ag particles are well distributed in the BCCO cobaltite matrix at low Ag contents. The Ag particles have an important effect on densification and grain orientation of the samples, with a direct impact on their electrical conductivity. The electrical conductivity is higher for the uniaxial samples and increases with the Ag content up to 20% in weight, while the Seebeck coefficient is hardly affected. These features induce an improvement of the power factor, reaching a maximum value of 2.2 μW K^?2 cm^?1 at ～1050 K for the uniaxial sample with 20 wt% Ag. Our results suggest that the spray-drying technique is a promising method to obtain composites with a well-dispersed secondary phase.     

Transfer of the chelating ligands in the systems [LAuCl2]+-[PdCl4]2−: Synthesis and structure of the salt (NH4)0.20[(Bipy)AuCl2]1.04[(Bipy)PdCl2]0.96[AuCl4]0.76[PdCl4]0.24

The formation of binary complex salts containing gold(III) in the cation and palladium(II) in the anion in the systems [(Bipy)AuCl₂]⁺-[PdCl₄]^2? occurs by transfer of the N,N-electron-donating chelating ligand bipyridine and the chloride ligands between the gold-containing cation and the palladium-containing anion. The resulting neutral salt [(Bipy)PdCl₂] crystallizes together with the anion [AuCl₄]^? from acetonitrile-water (1 : 1-1 : 2, v/v) to give the complex salt (NH ₄ ⁺ )_0.20[(Bipy)AuCl ₂ ⁺ ]_1.04[(Bipy)PdCl₂]_0.96[AuCl ₄ ^? ]_0.76PdCl ₄ ^2? ]_0.24 with a total Au : Pd ratio of 3 : 2. The ammonium cation is formed from acetonitrile upon its hydrolysis most likely catalyzed by Pd complexes. Quantum-chemical calculations were performed to study the transfer of the chelating ligand theoretically.     

Synthesis and characterisation of [tris(1,3-dithiole-2-thione-4,5-dithiolato)-stannate]2−, [Q]2[Sn(dmit)3], [tris(1,3-dithiole-2-one-4,5-dithiolato)stannate]2−, [Q]2[Sn(dmio)3] and [tris(1,3-dithiole-2-thione-4,5-selenolato)stannate]2−, [Q]2[Sn(dsit)3], complexes: Analysis of the structural variations of the [Sn(dmit)3]2− and [Sn(dmio)3]2− dianions

[Tris(1,3-dithiole-2-thione-4,5-dithiolato)stannate]²⁻, [Q]₂[Sn(C₃S₅)₃], [tris(1,3-dithiole-2-one-4,5-dithiolato)stannate]²⁻, [Q]₂[Sn(C₃S₄O)₃], and [tris(1,3-dithiole-2-thione-4,5-diselenolato)stannate]²⁻ [Q]₂[Sn(C₃S₃Se₂)₃], complexes, have been synthesised and characterised. Crystal structure determinations of [Q]₂[Sn(C₃S₅)₃] (Q=1,4-dimethylpyridinium, monoclinic and orthorhombic forms; NMe₄, NEt₄, and PPh₄) and [NEt₄]₂[Sn(C₃S₄O)₃] revealed variations in the overall dianion structures. The geometry about tin in each case is essentially octahedral with the chelate bite angles in the range 80.7(5)–87.45(4)°: the range of Sn–S distances is 2.5207(18)–2.571(17) Å. A statistical analysis, carried out on the crystal structure data for the six complexes, indicated that the most critical factors in controlling the overall shape of the dianion were the distances of the Sn atom from the dithiolate ligand planes [Sn–OOP]. Interanionic S⋯S interactions, within the sum of the van der Waals’ radii for two S atoms, are affected by the size of the cation, Q; the secondary connectivity is 3-dimensional for the smallest cations, Q=1,4-dimethylpyridinium and NMe₄, in chains for the somewhat larger cation, NEt₄ and is absent for the still larger, PPh₄ cation.     

[2＋2] Photocycloaddition of [60] Fullerene with Podophyllotoxin Derivative Containing Cyclohexadienone Group

Photochemical [2 2] cycloaddition of C60 with podophyllotoxin derivative containing a cyclohexadienone group in o-dichlorobenzene afforded an isomeric mixture of adducts and a pure adduct of C60-fused podophyllotoxin derivatives. The structures of the products were characterized by MS, NMR and IR spectra.     

Synthesis and Stuctural Characterization of the Complex [Et4N]2[Ni（C2S

The heteroleptic dmit complex [Et4N]2[Ni2(C2S4)(C3S5)2] has been prepared by the reaction of NiCl2.H2O with Na2dmit, NaSC2H4OH in the MeOH solution. The compound has been characterized by X-ray diffraction study, IR and UV-Vis spectroscopy. Crystallographic data : space group: P21/n, a=11.843(2), b=11.079(1), c = 15.404(1)(), β=110.33(1)°, V = 1895.1()3, Z=2, Dc=1.62 g/cm3, μ=17.6 cm-1, F(000)=956, R=0.052, Rw=0.061. In the structure of the title complex, the tto (tto=tetrathioxalato) ligand in bridging form is chelated to two nickel atoms and dmit (dmit=1,3-dithiole-2-thione-4,5-dithiolate) ligands coordinated to nickel atoms.     

The nature of the [TTF]˙+···[TTF]˙+ interactions in the [TTF]2(2+) dimers embedded in charged [3]catenanes: room-temperature multicenter long bonds

The properties of tetrathiafulvalene dimers ([TTF](2)(2+)) and the functionalized ring-shaped bispropargyl (BPP)-functionalized TTF dimers, [BPP-TTF](2)(2+), found at room temperature in charged [3]catenanes, were evaluated by M06L calculations. The results showed that their isolated [TTF](2)(2+) and [BPP-TTF](2)(2+) dimers are energetically unstable towards dissociation. When enclosed in the 4(+)-charged central cyclophane ring of charged [3]catenanes (CBPQT(4+)), [TTF](2)(2+) and [BPP-TTF](2)(2+) dimers are also energetically unstable with respect to leaving the CBPQT(4+) ring; since the barrier for the exiting process is only about 3 kcal mol(-1), that is, within the reach of thermal energies at room temperature (neutral [TTF](2)(0) dimers are stable within the CBPQT(4+) ring). However, the [BPP-TTF](2)(2+) dimers in charged [3]catenanes cannot exit, because this would imply breaking the covalent bonds of the BPP-TTF(+) macrocycle. Finally, it was shown that the [TTF](2)(2+), [BPP-TTF](2)(2+) dimers, and charged [3]catenanes are energetically stable in solution and in crystals of their salts, in the first case due to the interactions with the solvent, and in the second case mostly due to cation-anion interactions. In these environmental conditions at room temperature the TTF units of the [BPP-TTF](2)(2+) dimers make short contacts, thus allowing their SOMO orbitals to overlap: a room-temperature multicenter long bond is formed, similar to those previously found in other [TTF](2)(2+) salts and their solutions.     

CIDNP Study of Photoinduced [2 2] Cycloadditions (the PaternoBuechi Coupling) of Arylacetylenes and Quinone

CIDNP techniques were applied to study the mechanism of photocycloadditions of 2-chloro-5-methoxybenzoquinone 1 with arylacetylenes 2-5 in benzene-d6 and acetonitrile-d6 respectively.     

New Approach to Synthesis of Tetrahydroisoquino[2,l-c] [1,3]-benzodiazepine

A concise and efficient synthesis of the new compounds tetrahydroisoquino [2,1-c] [1,3] benzodiazepine 5 and 7 is reported.     

New approaches to the synthesis of functionally substituted pyrido[3′,2′:4,5]thieno[3,2-b]pyridines and the structure of the products obtained

Substituted pyrido,[3',2':4,5]thieno[3,2-b]pyndines were obtained by the reaction of 3-amino-2-benzoylthieno [2,3-b]pyridines with malononitrile and the reaction of 3-cyanopyridine-2(IH)-thiones with 2-aryl-3-bromo-I,I-dicyanopropene. 2-Amino-4-(4-bromophenyl)-7, 9-dimethyl-3-cyanopyrido [3',2':4,5]thieno[3, 2-b]-pyridine was used for the synthesis of a derivative of pyrido[3",2":4', 5']thieno[2',3':5,6]pyrido[2,3-d]-pyrimidine. The structure of these compounds was confirmed by spectral data and x-ray diffraction structural analysis.Deceased.     

A convenient synthesis of 2-aryl substituted benzo[f] [1,2,4]triazolo[1,5-a]azepine derivatives

A convenient synthetic pathway to 2-aryl-5,6-dihydro-4H-benzo[f][1,2,4]triazolo[1,5-α]azepine derivatives 7 was developed. The synthesis was based on the cycloaddition of the 1,2,3,4-tetrahydronaphthalene a-acetoxy azo compounds 3 with Ar-CN in the presence of AlCl3 and the consecutive ring enlargement.     

Novel Method for the Synthesis of [1,2,4]Triazino[4,3‐c]quinazoline System

4‐Hydrazinoquinazoline was found to form new 2‐(3,4‐dihydro‐3oxo‐2H‐[1,2,4]triazino[4,3‐c]quinazolin‐4‐yl)acetic acid with maleic anhydride in on‐step sequence. Proposed heterocyclization includes, probably, acylation reaction followed by intramolecular uncleophilic addition.     

The effect of styrene α-substituents on the regiochemistry of [2+2] cycloadditions with difluoroallene.

Consistent with our hypothesis for a mechanism involving two kinetically-distinct diradical intermediates, the observed effects of styrene α-substituents can be explained as deriving either from steric effects or radical stabilizing effects.     

Spectrophotometric study of melting of double stranded Poly[A]·Poly[U] in the aqueous solution

Experimentally observed changes in the electronic absorption spectrum of sodium salt of synthetic polyadenyl–polyuridyl acid (Poly[A]·Poly[U]) in the aqueous solution (pH = 7.0, I = 0.15 mol/L) with the change in temperature were explained in terms of co-existence of two different forms of the Poly[A]·Poly[U] strands. Chemometrics analysis of full set of melting curves measured at 120 wavelengths in the UV spectral range has been performed using evolving factor analysis (EFA) and KALS designed for the calculation of equilibrium constants from spectrometry data without a priori set model of the system. Using the Van’t Hoff equation, we have determined thermodynamic constants of the biopolymer transition from the double stranded helix into the random coil conformation (helix–coil transition), they can be further used to quantify the possibility of these structures to be involved in biochemical processes. Molecular model of partially denatured Poly[A]′·Poly[U]′ complex has been biult by means of molecular mechanics.