Xiaobo Wan

The electrochemical copolymerization of pyrrole and furan in a novel binary solvent system

Electrochemical copolymerization of furan and pyrrole was performed potentiostatically in a binary solvent system consisting of boron trifluoride ethyl ether and additional ethyl ether. The influence of applied polymerization potential and the monomer feed ratio of furan and pyrrole on the synthesis of copolymer was investigated. The higher potential favored the incorporation of furan units into the copolymer, while the amount of pyrrole units incorporated into the film increased with the increasing concentration of pyrrole in the solution. The film obtained was characterized by cyclic voltammetry, infrared and Raman spectroscopies.

Synthesis of high-quality polypyrrole in a binary solvent system consisting of boron trifluoride-ethyl ether and additional ethyl ether

Polypyrrole (PPy) was electrochemically synthesized in boron trifluoride ethyl ether (BTEE) whose acidity was adjusted with additional ethyl ether (EE). A high quality PPy film can be synthesized in a wide mole ratio range of BTEE/EE and under mild conditions. The obtained film showed the highest tensile strength (90 MPa) we had ever seen and good anisotropy in electrical conductivity. The structure was investigated using surface enhanced Raman scattering (SERS).

A multi-stimuli responsive organogel based on a tetrapeptide-dithienylcyclopentene conjugate

Multi-stimuli responsive organogels based on low-molecular-weight gelators (LMWGs) have attracted much attention due to their potential applications. Herein, the synthesis and the self-assembly behavior of a novel molecular gelator based on a tetrapeptide–dithienylcyclopentene conjugate is described. This gelator forms stable gels in THF, acetone and acetonitrile, in which the formation of anti-parallel β-sheets of the biomimetic tetrapeptides is the key driving force. Further studies suggest that the organogel is multi-responsive to various external stimuli including temperature, light, chemicals, and mechanical force. Moreover, in the presence of catechol, this gelator forms a more robust organogel, accompanied by a dramatic change of the assembly manner and rheological properties. These prominent features of this conjugate make it an excellent smart soft material with potential applications in areas such as drug encapsulation and release systems.

Benzo[f]benzo[5,6]indolo[3,2-b]indole: a stable unsubstituted 4nπ-electron acene with an antiaromatic 1,4-diazapentalene core

A stable unsubstituted 4nπ-electron acene with an antiaromatic 1,4-diazapentalene core was prepared via an unprecedented mild oxidation. Further investigation showed that the stability of such acenes was dependent on the fusion patterns of the peripheryl benzene rings to the centre core.

A Rapid and Efficient Access to Diaryldibenzo[b,f ][1,5]diazocines

2-Benzoylbenzoyl azides undergo facile cyclization under acidic conditions to give substituted dibenzo[b,f][1,5]-diazocines in good yields. This approach shortens the synthetic steps toward these compounds as compared with conventional methods. The mechanism of the diazocine synthesis is assumed to proceed by an unprecedented intermolecular [2 + 2] cyclization.

Thiophene-fused isoindigo based conjugated polymers for ambipolar organic field-effect transistors

A series of donor–acceptor (D–A) type conjugated polymers based on novel thiophene-fused isoindigo (TII) were designed and synthesized via palladium catalyzed Stille copolymerization. We found that the redesign of the synthesis of brominated TII was necessary, and the α-bromination had to be completed at the very beginning, or β-brominated TII was obtained, which only led to cross conjugated polymers. Once the bromination was introduced at the correct position, fully conjugated D–A type polymers could be obtained. A series of fully conjugated polymers were obtained by Stille coupling polymerization of α-brominated TII with different donors, and among them, copolymers with thiophene (T) and (E)-1,2-bis(3-octylthiophen-2-yl)ethene (TVT-8) showed acceptable solubility and were suitable to fabricate solution-processable organic field-effect transistors (OFETs). Top-gate/bottom-contact (TG/BC) devices were constructed for the polymers to test their OFET performances. Both fully conjugated polymers exhibit two-orders of magnitude higher charge carrier mobilities than the cross conjugated ones, and PTII-T shows balanced electron and hole mobilities and PTII-TVT-8 is a p-type dominated semiconductor. These observations indicated that the developed TII unit that has improved coplanarity can be a promising building block for the construction of highly efficient conjugated polymers for OFET applications.

Enantioselective total syntheses of trichodermamides A and B

Starting from commercially available (-)-quinic acid, the enantioselective total syntheses of trichodermamides A and B were achieved. The key reactions involve the stereoselective construction of the oxazine ring via an intramolecular epoxide ring opening reaction and an EDCI-assisted peptide coupling reaction.

Simple but Strong: A Mussel‐Inspired Hot Curing Adhesive Based on Polyvinyl Alcohol Backbone

The strong adhesion ability of mussel foot-byssal proteins (Mfps) has inspired scientists to develop novel materials for strong and reversible adhesion, coating, antifouling, and many other applications. However, in many cases, the high costs and the tedious preparation steps of such bioinspired materials hamper the process to push them into practical application. Here a simple but effective way (one step) is presented to synthesize a mussel-inspired glue from two cheap commercially available materials: polyvinyl alcohol (PVA) and 3,4-dihydroxybenzaldehyde (DBA). This bioinspired hot curing adhesive exhibits a strong bonding ability as high as 17.3 MPa on stainless steel surfaces, which surpasses most of the commercially available adhesives.

Extended isoindigo core: synthesis and applications as solution-processable n-OFET materials in ambient conditions

Two isoindigo derivatives fused with benzothiophene (C20-DBTII) and benzofuran (C20-DBFII) heterocycles have been synthesized. Solution-processed OFETs based on C20-DBTII showed ambient-stable ambipolar charge transport behaviour. OFETs based on the C20-DBFII show n-channel behaviour with electron mobility up to 0.074 cm2 V−1 s−1 in ambient conditions.

Oligothiophenes on CVD graphene grown on multi-crystalline copper foil: supramolecular assembly and impact of morphology

On graphene grown on copper foil, oligothiophenes form identical supramolecular assemblies on different copper facets. Most importantly, we found that the graphene ripple structures, even with a height as small as ~0.5 nm, can significantly alter the molecule-substrate interaction, which has never been observed previously.