Enhanced Hole-Injection Property in an OLED with a Self-assembled Monolayer of Hole-Transporting TPD on Thin Au as the Anode

A thioester-functionalized triphenylamine hole-transporting molecule(TPD-SAc) was synthesized and self-assembled to form a monolayer on an ultra-thin Au film supported on indium-tin oxide glass. The modified surface was characterized by aqueous contact angle, ellipsometer, atomic force microscopy, X-ray photoelectron spectroscopy, and ultraviolet photoelectron spectrometer to substantiate the formation of compact and pinhole-free monolayers. The modified organic light emitting diode device [indium-tin oxide/Au(5 nm)/self-assembled monolayers(SAM)/TPD(50 nm)/Alq_3(40 nm)/TPBI(15 nm)/LiF(1 nm)/Al(100 nm)] showed a luminance of 7303.90 cd/m^2 and a current efficiency of 8.49 cd/A with 1.78 and 2.29-fold increase, respectively, compared to the control device without SAM. The improvements were attributed to the enhanced compatibility of the organic–inorganic interface, matched energy level by introduction of an energy mediating step and superior hole-injection property of SAM molecules.

Facile Synthesis of [1,2,4]Triazolo[4,3-a]pyrazin-3-amines via Oxidative Cyclization of 1-(Pyrazin-2-yl)guanidine Derivatives

In this study, we applied a novel, mild, and convenient synthetic method involving the oxidative cyclization of 1-(pyrazin-2-yl)guanidine derivatives to produce [1,2,4]triazolo[4,3-a ]pyrazin-3-amines. We optimized the reaction procedure to easily obtain 5-chloro-[1,2,4]triazolo[4,3-a ]pyrazin-3-amine. Various types of halogenated pyrazines can successfully undergo this process. We synthesized a series of 1-(pyrazin-2-yl)guanidines and [1,2,4]triazolo[4,3-a ]pyrazin-3-amines, and then elucidated their structures based on their ~1H-NMR, ^(13)C-NMR, ESI-HRMS, and nuclear Overhauser effect spectra.

Recent Advances in Immobilization Strategies for Biomolecules in Sensors Using Organic Field-Eff ect Transistors

Organic fi eld-eff ect transistors(OFETs)are fabricated using organic semiconductors(OSCs)as the active layer in the form of thin fi lms.Due to its advantages of high sensitivity,low cost,compact integration,fl exibility,and printability,OFETs have been used extensively in the sensing area.For analysis platforms,the construction of sensing layers is a key element for their effi cient detection capability.The strategy used to immobilize biomolecules in these devices is especially important for ensuring that the sensing functions of the OFET are eff ective.Generally,analysis platforms are developed by modifying the gate/electrolyte or OSC/electrolyte interface using biomolecules,such as enzymes,antibodies,or deoxyribonucleic acid(DNA)to ensure high selectivity.To provide better or more convenient biological immobilization methods for researchers in this fi eld and thereby improve detection sensitivity,this review summarizes recent developments in the immobilization strategies used for biological macromolecules in OFETs,including cross-linking,physical adsorption,embedding,and chemical covalent binding.The infl uences of biomolecules on device performance are also discussed.

Engineering a cationic supramolecular charge switch for facile amino acids enantiodiscrimination based on extended-gate field effect transistors

Chiral recognition of essential amino acids(EAAs)is a huge challenge that keeps plaguing analytical scientists due to their cryptochirality and limited steric interaction sites.Inspired by the superior enantioselectivity of functional supramolecular cyclodextrins(CDs)and strong signal amplification ability of field effect transistors(FETs),this work firstly reports a cationic supramolecular charge switch for facile enantiodiscrimination of EAAs based on extended-gate organic FET(EG-OFET).The cationic phenylcarbamoylated-CD single isomer acts as a charge switch via interacting with different enantiomers and the weak stereo-differentiation intermolecular interaction signals between the cationic perphenylcarbamoylated CDs and EAAs on the EG can be strongly and rapidly amplified through an OFET.Efficient chiral differentiation of six EAAs,including phenylalanine,tryptophan,leucine,isoleucine,lysine and valine,are successfully achieved without any derivation process and the detection limit for D-phenylalanine is down to 10^(-13)mol/L.We believe that this study provides a new and facile sensing perspective for natural amino acids and may afford deeper understanding of molecular chirality.

Cyclodextrin derivatives functionalized highly sensitive chiral sensor based on organic field-effect transistor

Novel highly sensitive chiral organic field-effect transistors(COFET)were developed by directly assembling imidazolium3,5-dimethylphenylcabamoylated-β-cyclodextrin(lm^+-Ph-β-CD)and 3,5-dimethylphenylcarbamoylated-β-CD(Ph-β-CD)respectively onto the semiconductor layer as sensing units.The Im+-Ph-β-CD/COFET afforded better enantioselectivity and a lowest detection concentration of10^-18 L/mol as well as the potentiality in quantitative analysis of commercial medicines.

Piezochromic luminescence and aggregation induced emission of 9,10-bis[2-(2-alkoxynaphthalen-1-yl)vinyl]anthracene derivatives

Four derivatives of 9,10-bis[2-（2-alkoxynaphthalen-1-yl）vinyl]anthracene（BNAs） were designed,successfully synthesized and characterized by spectrofluorometer, powder wide-angle X-ray diffraction（PXRD） and differential scanning calorimetry experiments（DSC）, etc. It was found that these compounds exhibited aggregation-induced emission phenomenon. Moreover, these target compounds displayed reversible color change from yellow to orange upon pressing and annealing process. Interestingly, all of BNAs obviously presented red-shifted piezofluorochromic（PFC） properties and behaved mainly length dependence of alkoxy group, in which, BNA displayed the largest PFC spectral shift（DlPFC= 26 nm）. The PXRD profiles demonstrated the transformation from crystalline to amorphous state upon grinding, and the mechanism of PFC behaviors was proposed. Thus, changing the length of alkoxyl chain could be an alternative way to tune their PFC behaviors.

The gelation rule of the polyol acetal derivatives in binary solvent mixtures

The gelation properties of polyol acetal derivatives including 2,4-（3,4-dichlorobenzylidene）-D-sorbitol（DCBS）, 1,3：2,4-di（3,4-dichlorobenzylidene）-D-sorbitol（DDCBS） and 1,3：2,5：4,6-tris（3,4-dichlorobenzylidene）-D-mannitol（TDCBM） in 35 single solvents and 39 binary solvent mixtures have been studied. FTIR and XRD results suggest that the self-assembly patterns of the gelator will not change in either the single solvent component or the corresponding solvent mixtures, but the critical gelation concentration（CGC）will be influenced. The results of SEM and rheology showed that the formation of true gels at saturated concentrations. Improving the heating temperature may promote the dissolving of gelators which are even insoluble at the temperature of the solvent boiling point and change the gelation behaviors. FloryHuggins parameter（x） was used to predict the gelation behavior of DCBS in the mixed solvents, and it is shown that the x values for the mixed solvents that can be gelled by DCBS are either greater or smaller than those for the selected good solvents.

A facile and green strategy to obtain organic room-temperature phosphorescence from natural lignin

Seeking pure organic functional luminescent materials that are processed from green, low-cost, and sustainable resources remains a challenging but beneficial task. As an abundant natural polymer composed of crosslinked phenol ether units, lignin is a potential source of organic luminescent material because of the presence of extensive aromatic fragments. In the present work, a remarkable afterglow involving room-temperature phosphorescence(RTP) was achieved via simply embedding alkalized lignin into polyvinyl alcohol(PVA) matrix, and an ultralong luminescence lifetime of more than 160 ms was observed. More importantly, our study revealed that small fragments of hydrolyzed lignin(named LA-H) bearing extensive phenolic oxygen anions were the effective luminescent species. When embedded into a PVA matrix, LA-H showed remarkably high luminescence quantum yield and long lifetime of RTP emission compared with those of unprocessed lignin. Additionally, the various phenol oxygen anion moieties endowed LA-H with an excitation-dependent characteristic: the color-tunable RTP could be simply tuned from a maximum emission wavelength of 434–532 nm via altering the excitation wavelength. Thus, the color-tunable afterglow of emissive LA-H could be facilely obtained with a yield up to 38.4% using simple acid hydrolysis of lignin without other complex synthesis procedures. This work opens new avenues in the large-scale preparation of low-cost and sustainable pure organic RTP materials.

Two near-infrared highly sensitive cyanine fluorescent probes for pH monitoring

Two near-infrared（NIR） p H-activated heptamethine indocyanine probes with quaternary ammonium unit were designed and synthesized. The absorption and emission titrations indicate that cationic structure improves the cyanine dye＇s aqueous solubility and these two probes exhibit highly sensitive response to p H in acid condition. Their fluorescence intensities both gradually increase about 25-fold from p H 7.60 to 3.00 with p Ka values of 4.72 and 4.45 respectively, which are suitable for studying acidic organelles in living cells. Moreover, their fluorescence intensities are linearly proportional to p H values in the range of 5.50–4.00. These results are probably attributed to the protonation of the indole nitrogen atoms, which are verified by 1H NMR spectra. Furthermore, these two probes can achieve real-time imaging of cellular p H and detection of p H in situ in living He La cells due to their excellent properties,including good reversibility, desirable photostability, high selectivity, low cytotoxicity and remarkable membrane permeability.

刺激响应红色发光体:痕量水及相对湿度的检测（英文）

本文设计并开发了一种以吡喃酮和三苯胺为母体的多刺激响应D-A型化合物(CYQ).目标产物表现出优异的聚集诱导发光增强性能(AEE).溶剂变色实验及密度泛函理论表明CYQ具有极强的分子内电荷转移(ICT)性质.粉末广角X射线衍射(PXRD)及差式扫描量热法(DSC)证明了在外力作用下,分子由晶态向无定型态的转变.研究发现, CYQ对有机溶液中的痕量水非常敏感,在四氢呋喃(THF)中可达到极低的检出限0.0096%.除此之外,随着湿度的增加, CYQ的荧光强度呈现逐渐下降趋势.这一相对湿度检测法为该AIE材料成为不同环境下的比色探针提供了可能.