SYNTHESIS AND CHARACTERIZATION OF A NOVEL BLUE LIGHT EMITTING ROD-COIL DIBLOCK OLIGOMER

Four new rod-coil diblock molecules, which had well-defined para-phenylene oligomers (PPP, from biphenyl to quinquephenyl) as rigid segments and poly(ethylene oxide) (PEO, M-w ca. 750) as flexible segments, were synthesized. The chemical structure and the number of repeating unit in PEO coil and PPP rod were characterized by H-1-NMR and MALDI-TOF mass spectrometry. The diblock oligomers showed good solubility in common organic solvents and aggregated in water as characterized by a blue shift in UV-vis absorption spectra, a red shift in emission spectra, quenching of the fluorescence and formation of the microfibrilla and fractal-like structures. The formation of different supramolecular structures meant that this effort might lead to commercial important highly organized functional materials.

Visualized thermoresponsive helix-helix switch of polyphenylacetylene with a wide-range tunable transition temperature

Polymers with tunable helicity and naked-eye structural change under external stimuli are valuable for fabricating smart materials. Herein, we report a novel thermoresponsive color and fluorescent polyphenylacetylene switch with a tunable critical temperature. It relies on the temperature and solvent sensitivity of intramolecular n→π* interactions between the vicinal carbonyl groups of ester substituents located at 3,5-positions, which are indispensable for forming the cis-cisoid helical conformation of polyene backbones. In a properly chosen solvent, a compressed cis-cisoid helix is stabilized by n→π* interactions at low temperatures and yields a colorless solution. Increasing temperature causes the conformational transition toward an extended cis-transoid helix due to the disruption of n→π* interactions and produces a yellow solution. Reducing the hydrogen bond donating ability or polarity of solvents increases the switching temperature. By introducing a fluorogenic pendant, this conformational transition can also be read out by fluorescence quenching. This work may open a new window for developing intelligent materials through precisely tuning conformational transitions.

文章知己 患难夫妻 翁雒《鸿案联吟图》卷题咏试探

一引言:朗抱蟾宫同照影,良缘鸿案永齐眉晚清震泽张澹、陆惠伉俪情深,相互尊重,引为楷模。他们恩爱默契,风流潇洒,谈诗论艺,联吟唱和,好不自在,不仅刊印《玉巢燕双声合刻》(图1),还先后延请吴江翁雒(1790-1849)、乌程费丹旭(1802-1850)造像《鸿案联吟图》,互学同乐,演绎佳话。而且,张澹有意宣扬,二十余年间携册出行,持之以恒地邀题索题,并引为自得。翁雒创作《鸿案联吟图》(图2),应在《玉巢燕双声合刻》刊梓不久,约于道光八、九年(1828-1829)间,展示了张澹、陆惠夫妇“疏雨茅檐底,联吟极有情”^(1)的诗画志趣。

Effect of stereoregularity on excitation-dependent fluorescence and room-temperature phosphorescence of poly(2-vinylpyridine)

Preparation of non-conjugated luminescent polymers(NCLPs)with excellent cluster luminescence(CL)performance is of great significance for scientific and industrious applications,and yet improving the performance of NCLPs through proper structural design is still a huge challenge.Herein,we report a non-conjugated ionized polymeric system consisting of(−)-camphorsulfonic acid((−)-CSA)and poly(2-vinylpyridine)(P2VP).These acid-base complexes exhibit typical excitationdependent fluorescence and room-temperature phosphorescence(RTP)with a lifetime up to 364 ms.We discover that changing the stereoregularity from atactic to isotactic significantly improves the CL performance of the complex.It(1)broadens the fluorescence emission spectra to cover the entire visible region,(2)enhances the fluorescence emission intensity at long wavelength beyond 500 nm,(3)enhances the phosphorescence intensity,and(4)extends the phosphorescence lifetime.Systematical experimental characterization and molecular dynamics simulation unravel the key role of stereoregularity in determining the formation of different pyridine aggregates that strongly influence the CL performance.Moreover,the different luminescence shows great potential in excitation divided information display and time-resolved encrypted display.This work not only points to a new direction for developing NCLPs with excellent performance,but also broadens the applications of NCLPs materials.

The recommendations of Chinese Parkinson’s disease and movement disorder society consensus on therapeutic management of Parkinson’s disease

Background:Parkinson’s disease(PD)is a chronic,progressive and debilitating disease,which affects over 2.5 million people in China.PD is characterized clinically by resting tremor,muscular rigidity,bradykinesia and postural instability.As the disease progresses,additional complications can arise such as non-motor and neurobehavioral symptoms.Pharmacological treatment and surgical intervention for PD have been implemented in China.Until 10 years ago,there was lack of standardization for the management of PD in different regions and among different physicians,leading to different treatment levels in different regions and different physicians.Since then,the Chinese Parkinson’s Disease and Movement Disorder Society have published three versions of guidelines for the management of PD in China,in 2006,2009 and 2014,respectively.Correspondingly,the overall level of treatment for PD in China improved.Objectives:To update the treatment guidelines based on current foreign and domestic practice guidelines and clinical evidence,and to improve the treatment options available to physicians in the management of PD.Summary:A variety of treatment recommendations in the treatment guidelines have been proposed,including physical activity and disease-modifying medication,which should be initiated at the early-stage of the disease.The principles of dosage titration should be followed to avoid acute adverse reactions to the drugs,to achieve a satisfactory clinical effect with a low dose and to reduce the incidence of long-term motor complications.Moreover,different treatment strategies should be considered at different stages of the disease.Importantly,treatment guidelines and personalized treatments should be valued equally.A set of treatment recommendations has been developed to assist physicians to improve and optimize clinical outcomes for patients with PD in China.

Special topic on recent progress in electrochromism

Electrochromism is a phenomenon known as reversible optical property change of some materials in transmittance,reflectance,or absorbance in response to an external electric potential.With the huge potential market in the fields such as building window,vehicle window and mirror,and display,state-of-the-art researches on electrochromism may possess significant impact on environment,economy and society.

Doublet Chirality Transfer and Reversible Helical Transition in Poly(3,5-disubstituted phenylacetylene)s with Pyrene as a Probe Unit

A novel doublet chirality transfer(DCT)model was dem on strated in cis poly(3,5-disubstituted phenylacetylene)s,i.e.,S-l,R-l,and S-l-NMe.The chiral message from the stereocentwr of alkylamide substituent at 3-position induced the polyene backbone to take cis-transoid helical conformation with a predominant screw sense.And in turn the helical backbone acted as a scaffold to orient the pyrene probes,which was linked to phenyl rings through 5-position,to array in an asymmetric manner.A combinatory analyses of 1H NMR,Raman,FTIR,UV-vis absorption,CD,and computer simulation suggested that the main-chain stereostructure,solve nt nature,and intramolecular hydrogen bonds played important and complex roles on DCT.High c/s-structure content and intramolecular hydrogen bonds were beneficial for the realization of DCT.Reversible helix-helix transition was observed in S-l by changing the nature of solvents.In DMF,S-l adopted a relatively contracted helix,where the main chain exhibited strong optical activity,but that of pyrene was weak.In contrast,a relatively stretched helix formed in CHCI3/in which the optical activity of pyrene was much larger,whereas that of the polye ne backbone was the weakest.This helix-helix transition was attributed to the intramolecular hydrogen bon ds,which was confirmed by solution-state FTIR spectra and computer calculations.

Halogen effects on phenylethynyl palladium(Ⅱ) complexes for living polymerization of isocyanides

Polyisocyanides belong to one of the most important artificial helical polymers. The rigid-rod helical conformation makes them to exhibit wide potential applications in chiral recognition, enantioseparation, asymmetrical catalysis, and liquid crystals [1]. Up to now, quite a few metal-promoted polymerization methods have been developed to synthesize polyisocyanides. Especially, it is a great challenge for synthetic chemists to synthesize polyisocyanides in living/controllable fashion that afford well-defined and high isotactic helical polymers.

High-performance nano-splitters containing aggregation-induced emission luminogens for stereoselective crystallization obtained via polymerization-induced self-assembly

Collecting both enantiomorphs with high optical purity and yield in a single crystallization process can be achieved by adding aggregated polymeric“tailor-made”additives,known as nano-splitters.Inefficient preparation and large addition amount have hindered the practical application of such amazing nanoparticles.Herein,we report the first nano-splitters containing aggregation-induced emission luminogens prepared via polymerization-induced self-assembly of block copolymer,poly[(S)-2-(tert-butoxycarbonylamino)-6-(methacrylamido)hexanoic acid]-b-polystyrene,followed by the removal of tert-butoxycarbonyl groups.When added into the supersaturated solution of racemic amino acids(a.a.)with seeds,the fluorescent labeled nano-assemblies enantioselectivity dyed the crystals of S-a.a.and enabled the separation from colorless R-a.a.crystals in terms of fluorescent difference.Both enantiomers were obtained with high optical purity and yield(e.g.,R-asparagine monohydrate,>99 ee%;S-asparagine monohydrate,∼94 ee%;88%total yield).Owing to a low detection limit of fluorescence,the addition amount was reduced to 0.03 wt%without remarkably compromising the ee values of both enantiomorphs.Due to the low addition amount and efficient synthesis,the output–input ratio was increased greatly.