A twin-axial[5]pseudorotaxane based on cucurbit[8]uril and a-cyclodextrin

A twin-axial hetero[5]pseudorotaxane was constructed based on 1-hexyl-4,40-bipyridinium guest 1 and cucurbit[8]uril（CB[8]）and a-cyclodextrin（a-CD）.In its structure,CB[8]included two bipyridinium units to realize the twin-axial mode,and the hexyl chain was threaded into the cavity of a-CD.The[5]pseudorotaxane contains two types of macrocyclic hosts while the single axial and twin axial modes co-exist in its structure.The transformation of[5]pseudorotaxane could be realized by the addition of acid and 2,6-dihydroxynaphthalene（HN）.     

Supramolecular electronics; nanowires from self-assembled pi-conjugated systems

The conditions required for supramolecular electronics, e.g. nano-sized optoelectronic devices, will be illustrated on the basis of the programmed self-assembly of pi-conjugated systems into individual nanosized wires. Using the supramolecular design rules nanowires can be created from almost any polymeric and oligomeric pi-conjugated system. In the case of oligomers it is even possible to construct individual wires having a uniform diameter of one molecule thickness. The construction of wires on a substrate is possible by self-assembly in solution or during the deposition. The transfer of the supramolecular stacks from solution to a solid support is a very delicate process. A comprehensive knowledge of all intermolecular interactions gives rise to controlled transfer of pi-conjugated assemblies to specific surfaces. There are a large number of very appealing targets that should be reached before supramolecular electronics can serve as an attractive alternative in between single molecule electronics and bulk devices. Nevertheless, the combination of exciting scientific results and intriguing technological challenges creates an interesting future for supramolecular electronics.     

Aromatic single-walled organic nanotubes self-assembled from NH-bridged azacalix[2]triptycene[2]pyridine

A novel triptycene-derived NH-bridged azacalixarene can self-assemble into an aromatic single-walled organic nanotube with large dimensions by four one-dimensional hydrogen bond chains.     

Guest-encapsulation behavior in a self-assembled heterodimeric capsule

Tetra(4-pyridyl)-cavitand 1 and tetrakis(4-hydroxyphenyl)-cavitand 2 self-assemble into a heterodimeric capsule 1·2 via four PhOH?pyridyl hydrogen bonds in CDCl₃, wherein one molecule of 1,4-disubstituted-benzene as a guest is encapsulated to form a ternary complex, guest@(1·2). The X-ray crystallographic analysis of (methyl p-ethoxybenzoate)@(1·2) confirmed that the methyl ester and ethoxy groups of the encapsulated guest are oriented to the cavity ends of the 1 and 2 units, respectively. The scope and limitation of guest encapsulation in 1·2, including guest-binding selectivity and orientational isomeric selectivity, are described from the viewpoint of size complementarity and CH-π, CH-halogen, and halogen-π interactions between guest and the cavity of 1·2.     

Detection of cationic guest molecules by quenching of luminescence of a self-assembled host molecule consisting of terbium(III) and calix[4]arene-p-tetrasulfonates

By self-assembly in aqueous solution, calix- (CAS) and thiacalix[4]arene-p-tetrasulfonate (TCAS) formed luminescent complexes Tb^III·(CAS)₂ and Tb^III·TCAS, respectively, which were utilized as a host for cationic guests. Addition of 1-ethylpyridinium guest quenched luminescence of Tb^III·(CAS)₂ in accordance with the Stern-Volmer (SV) relation with a low detection limit (D.L.) of 5.94 × 10⁻⁸ M (S/N = 3, M ≡ mol dm⁻³). On the other hand, 1-ethylquinolinium quenched luminescence of Tb^III·TCAS most efficiently, affording a very low D.L. (6.71 × 10⁻¹⁰ M). The agreement of the SV coefficients obtained with luminescent intensity (K_SV,all = 6.74 × 10⁶ M⁻¹) and lifetime (K_SV,Tb = 6.50 × 10⁶ M⁻¹) implied that dynamic quenching of ⁵D₄ excited state of Tb^III was predominant in the quenching processes. The quenching rate was estimated to be k_q,Tb = 9.94 × 10⁹ M⁻¹ s⁻¹, which was as fast as diffusion-limited rate. Quenching of Tb^III·(CAS)₂ was also applied to detection of NAD⁺, with a D.L. of 2.78 × 10⁻⁷ M.     

One-dimensional HKUST-1 nanobelts from Cu nanowires

The controllable synthesis of one-dimensional(1D) structural morphology of metal-organic frameworks(MOFs) is significant for its application in catalysis,sense and gas separation.In this communication,we report a simple and moderate synthetic strategy to obtain uniform HKUST-1 nanobelts(NBs) by using copper nanowires(Cu NWs) as a metal source as well as a template.The control experiments showed that synergy between metal dissolution rate and crystal formation plays a key role in the formation of nanobelts.Our study represents an attractive synthetic strategy of 1 D MOFs-based material for applications.     

Monofunctionalized pillar[5]arene-based stable [1]pseudorotaxane

A new monofunctionalized pillar[5]arene bearing imidazolium moiety that formed stable [1]pseudorotaxane even at high concentration (100 mmol/L) was reported. [1]Rotaxane was obtained effi ciently through thiol-ene reaction from [1]pseudorotaxane which further confi rmed the formation of [1]pseudorotaxane.     

[60]富勒烯的超分子自组装研究进展

超分子自组装是发展超分子电子学的重要途径。随着纳米科学和技术的迅速发展,自组装技术已成功地应用于纳米尺度物质的维数、形貌和功能等的调控。作为构筑分子水平上一维、二维、三维有序功能结构和高有序分子聚集态结构的关键技术,超分子自组装技术有力地推动了具有优良光、电、磁性能的分子材料和纳米功能材料更深层次的研究。本文综述了超分子自组装在富勒烯科学领域的基础研究和应用,特别是对有利于自组织和自组装功能的富勒烯基衍生物的设计与合成、超分子作用力引导的具有特定结构的分子体系的可控自组装、以及富勒烯分子聚集态结构材料的光物理过程、超分子中电子转移和能量转移现象进行了描述;并对卟啉、四硫富瓦烯、碗烯和杯芳烃等一系列富π电子化合物和大环主体分子等包含[60]富勒烯的主体化合物的超分子作用和超分自组装体以及通过氢键、π-π作用、静电力和范德华力和金属配位作用形成的[60]富勒烯超分子自组装体进行了总结,对未来发展进行了展望。     

Synthesis of anthra[b]thiophenes and benzo[b]naphtho[d]thiophenes

All isomers of the parent anthra[b]thiophenes and benzo[b]naphtho[d]thiophenes, namely anthra[2,3-b]thio-phene, anthra[2,1-b]thiophene, anthra[1,2-b]thiophene, benzo[b]naphtho[2,3-d]thiophene, benzo[b]naphtho[2,1-d]thiophene and benzo[b]naphtho[1,2-d]thiophene were synthesized using a new procedure.     

Electrochemical reactivity and fractional conductance of nanowires

A theory for electrocatalysis devised in the authors’ group is combined with density functional theory to investigate the electrochemical reactivity of monoatomic nanowires towards hydrogen. On Cu and Au wires, hydrogen atoms are much more strongly adsorbed than on planar surfaces of the bulk metal, while on Ag adsorption is weak. These results explain recent observations of fractional conductances on electrochemical Cu and Au nanowires in the hydrogen evolution region. Free energy surfaces for the adsorption and discharge of the proton show low activation barriers of the order of 0.1 eV for Au and 0.5 eV for Cu. Thus, both Au and, most surprisingly, Cu wires promise to be good catalysts for hydrogen evolution.     

Unique self-assembly patterns based on thiacalix[4]arene-silver interactions

Novel self-assembled supramolecular networks were prepared by the interactions of thiacalix[4]arenes bearing simple alkyl groups on the lower rim (4×MeO-, 4×n-PrO-) with silver triflate. Contrary to the classical calix[4]arenes (with CH₂ bridges between the aromatic moieties), the presence of four sulfur atoms enables the formation of S-Ag-S connections between the individual molecules leading to the coordination topology so far unknown in calixarene chemistry. These systems form infinite 1-D coordination polymeric structures in the solid state, where the thiacalixarene moieties are preorganized in a side-by-side arrangement. Interestingly, the linear coordination polymers were obtained using both the conformational immobilised (4×n-PrO, cone, 1,3-alternate conformers) and the conformational mobile (4×MeO) thiacalix[4]arenes, which indicates the generality of this behaviour in thiacalixarene series.     

The synthesis of benzo[b]phenanthro[d]thiophenes and anthra[b]benzo[d]thiophenes

The synthesis of benzo[b]phenanthro[2, 3-d]thiophene ( 5 ), benzo[b]phenanthro[4, 3-d]thiophene ( 6 ), benzo-[b]phenanthro[2, 1-d]thiophene ( 9 ), benzo[b]phenanthro[3, 2-d]thiophene ( 14a ), anthra[1, 2-b]benzo[d]thiophene ( 24 ), anthra[2, 3-b]benzo[d]thiophene ( 29 ) and anthra[2, 1-b]benzo[d]thiophene ( 30 ) is described as well as the preparation of 13-methylbenzo[b]phenanthro[3, 2-d]thiophene ( 14b ).     

1H NMR spectra of benzo[b]furan,benzo[b]thiophene and benzo[b]selenophene oriented in a lyotropic mesophase

The proton nuclear magnetic resonance spectra of benzo[b]-furan, -thiophene and -selenophene oriented in a potassium laurate lyotropic liquid crystal have been analyzed. Geometrical information has been obtained and compared to previous thermotropic results and various hypothetical models.     

Self-assembly and proton conductance of organic nanotubes from pillar[5]arenes

Organic nanotubes have been assembled from pillar[5]arenes 1 and 2. Compound 1 gelates organic solvents through the formation of tubular fibers which are evidenced by TEM and XRD experiments, while 2 assembles into two different channels under the template effect of water wires. In addition, the water wires in the nanotubes of 2 can be under selective proton conductance. The results described herein represent a new strategy for building tubular structures.     

New reaction of benzo[b]thieno[3,2-b]benzo[b]thiophene disulfone

A new reaction of benzo[b]thieno[3,2-b]benzo[b]thiophene disulfone with amines that takes place with opening of one of the thiophene rings and nucleophilic substitution in the heteroaromatic ring at the site of cleavage of the S-C bond was observed. The molecular structures of the products of amination of the disulfone were determined by x-ray diffraction analysis. Hydrolysis and dehydration of the amination products gave derivatives of a new heterocyclic system, viz., benzo[b]-thieno[3,2-e]benzo[c]-1,2-oxathiin. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 320–323, March, 1980.     

Oxidation triggered structural transformations of a self-assembled telluropeptide

Here, we report the details of the synthesis and characterization of tubular molecular self-assembly of designed telluropeptide 1 at physiological pH conditions. The telluropeptide nano-/microtubes transformed into solid/hollow spheres or vesicles and ring-like structures upon controlled oxidation of telluro-amino acid residues present in the sequence of telluropeptide 1 by hydrogen peroxide.     

Electrochemical formation and investigation of a self-assembled [60]fullerene monolayer

The formation and characterisation of a C(60) monolayer at the electrode|electrolyte interface has been studied by cyclic voltammetry, potential step chronoamperometry and ac voltammetry. The presence of the monolayer is evidenced by the presence of a very sharp peak P in the voltammogram, attributed to the faradaic phase formation of an ordered monolayer, and of a reduction post peak Q associated with the reduction of adsorbed species. The chronoamperograms exhibit a well-defined maximum, characteristic of a nucleation and growth mechanism. By comparison with existing models of phase transitions, a progressive polynucleation and growth mechanism is demonstrated. The monolayer is proposed to consist of a 2D fulleride salt. It is suggested that the formation of the monolayer can take place for a broad range of solution compositions, but requires an atomically smooth substrate such as mercury.     

Sulfur-rich heterocycles from 2-metalated benzo[b]thiophene and benzo[b]furan: synthesis and structure

The reaction of 2-lithiated benzo[b]thiophene with 8 equiv of elemental sulfur was found to give pentathiepino[6,7-b]benzo[d]thiophene. In contrast, treatment of 2-lithiated benzo[b]furan with sulfur under similar conditions produced the interesting ring system bis(benzo[4,5]furo)[2,3-e:3',2'-g][1,2,3,4]tetrathiocine. Both of these new cyclic polysulfides were studied by X-ray crystallography. Two polymorphic forms of pentathiepino[6,7-b]benzo[d]thiophene were found, displaying similar conformations but different packing schemes, which was also evident from powder diffraction data.     

Single tungsten nanowires as pH sensitive electrodes

The electrochemical potentials of tungsten nanowire samples, covered with their own oxide, were measured in dependence of the pH value. The samples were prepared by selective etching of a directionally solidified eutectic NiAl–W alloy. Directional solidification in a Bridgman-type crystal growth furnace yields nanostructured two-phase materials. Electrochemical processing allows selective etching of the phases exposing the nanoscale structures. In this work, pointed samples with a single wire 200 nm in diameter protruding from the tip were produced. Subsequently the tungsten oxide layer on these single nanowires was electrochemically modified to optimize their pH sensing capabilities. The method has a potential for further downsizing since the wire diameter and exposed length can be controlled by the process parameters during solidification and during electrochemical processing. The advantages of these nanowire pH probes along with possible applications such as the pH measurement in ultra small cavities and other small systems of interest such as corrosion pits and biological cells are discussed.