Synthesis and characterization of red-emission PPV copolymers containing fluorenone unit

Two soluble copolymers of fluorenone and dioctoxylbenzene （PFN） or anthracene （PFNAn） were synthesized through Heck polymerization, and were characterized by gel permeation chromatography （GPC）, FT-IR, IH-NMR, elemental analysis and thermogravimetric analysis. The polymers possess good solubility in common organic solvents and high thermal stability with the Onset decomposition temperature at higher than 410 ℃. The photophysical properties of the polymers were investigated in both solutions and spin-coated films. Cyclic voltammetry results revealed that the copolymers possess higher electron affinity and reversible reduction/re-oxidation processes. Their electroluminescent properties were further investigated. PFN and PFNAn show stable and saturated red light emission with high thermal stability and high electron injection ability. This type of conjugated polymers may be promising for the applications as electron acceptors in polymer photovoltaic cells and electron transporting materials.

Red-emission organic light-emitting diodes based on solution-processable molecules with triphenylamine core and benzothiadiazole-thiophene arms

We report red-emission organic light-emitting diodes (OLEDs) based on solution-processable organic molecules with triphenylamine (TPA) as core and benzothiadiazole-(4-hexyl)thiophene (BT-4HT) as arms.Bi-armed molecule B(TPA-BT-4HT) and star-shaped (tri-armed) molecule S(TPA-BT-4HT) both show pure red-emission peaked at 646 and 657 nm,respectively.The red-emission OLED with S(TPA-BT-4HT) as the emitting layer displays a higher maximum luminance of ca.7794 cd/m2 and a maximum EL efficiency of 0.91 cd/A.

Constructing D-π-A-π dye to obtain red-emission fluorescent probe for structured illumination microscopy imaging of lipid droplet dynamics

Lipid droplets(LDs)are dynamic organelles interacting with a variety of intracellular organelles.Tracking intracellular LD dynamics employing synthetic small molecules is crucial for biological studies.Fluorescence imaging in the red and near infrared(NIR)region is more suitable for biological imaging due to its low phototoxicity and high signal-to-noise ratio.However,available LD-dyes in the red region with remarkable environmental sensitivity,selectivity for LDs staining are limited.Here,we constructed a red-emission D-π-A-π type LDdye LD 688P with higher environmental sensitivity and suitable“calculated log P”(Clog P)for LDs dynamic imaging.LD 688P was proved to be highly selective and photostable for tracing LD fusion including multiple consecutive fusions and fusions in a centrosymmetric manner by super-resolution microscopy.We believe that the D-π-A-π skeleton would be an efficient strategy to construct red and even NIR-emission dyes.

Photoluminescence mechanisms of red-emissive carbon dots derived from non-conjugated molecules

Red-emissive carbon dots(R-CDs)have been widely studied because of their potential application in tissue imaging and optoelectronic devices.At present,most R-CDs are synthesized by using aromatic precursors,but the synthesis of R-CDs from non-aromatic precursors is challenging,and the emission mechanism remains unclear.Herein,different R-CDs were rationally synthesized using citric acid(CA),a prototype non-aromatic precursor,with the assistance of ammonia.Their structural evolution and optical mechanism were investigated.The addition of NH_(3)·H_(2)O played a key role in the synthesis of CA-based R-CDs,which shifted the emission wavelength of CA-based CDs from 423 to 667 nm.Mass spectrometry(MS)analysis indicated that the amino groups served as N dopants and promoted the formation of localized conjugated domains through an intermolecular amide ring,thereby inducing a significant emission redshift.The red-emissive mechanism of CDs was further confirmed by control experiments using other CA-like molecules(e.g.,aconitic acid,tartaric acid,aspartic acid,malic acid,and maleic acid)as precursors.MS,nuclear magnetic resonance characterization,and computational modeling revealed that the main carbon chain length of CA-like precursors tailored the cyclization mode,leading to hexatomic,pentatomic,unstable three/four-membered ring systems or cyclization failure.Among these systems,the hexatomic ring led to the largest emission redshift(244 nm,known for CA-based CDs).This work determined the origin of red emission in CA-based CDs,which would guide research on the controlled synthesis of R-CDs from other non-aromatic precursors.

Design of activatable red-emissive assay for cysteine detection in aqueous medium with aggregation induced emission characteristics

A novel wate r-soluble red-emissive AIE fluorescence probe for cysteine(Cys) in situ was prepared and the performance of selectivity and sensitivity has been carefully investigated in this study.The probe was established on the electrostatic interaction of sulfonate functionalized tetraphenylethene(TPE) and polycation generated by the reaction between a polymer bearing dinitrobenzenesulfonate groups and Cys.From the experimental results,it was easy to distinguish Cys from glutathione(GSH) and homocysteine(Hcy) with a detection limit of 73 nmol/L.The assay system also possessed strong antiinterference ability against multitudinous amino acids.The Stokes shift was 142 nm and the emission ranged from 550 nm to 850 nm.In addition,double responses in fluorescence and ultraviolet-visible spectra also make the red-emissive assay ideal for sensitive detection and quantification of Cys for most purposes,especially in-situ monitoring of Cys in aqueous medium.

Red-Emissive Organic Room-Temperature Phosphorescence Material for Time-Resolved Luminescence Bioimaging

Organic room-temperature phosphorescence(RTP)materials have been used in high-resolution imaging.However,the development of long-wavelength-emis sion RTP materials in aqueous solution remains a challenge.Here,we report red-emissive RTP materials via integration of the ring-fusing effect and host–guest interaction.

Quantitative detection of citrate for early stage diagnosing of prostate cancer:Discriminating normal to cancer in prostate tissues

Prostate cancer(PC)biomarker-citrate detection is clinically important to diagnose PC in early stages.Methylquinolinium iodide(Q)conjugated indole-phenylboronic acid(IB)was designed as a red-emissive QIB probe for the detection of citrate through Lewis acid-base reaction and intramolecular charge transfer(ICT)sensing mechanisms.Boronic acid acts as Lewis acid as well as citrate(Lewis base)recognition unit.The probe reacted with citrate,showing enhanced red emissions.Since the probe has excellent water solubility and great biocompatibility,practical application in biological systems is possible.Citrate was monitored precisely in the mitochondria organelle(in vitro)of living cells with a positive charge on QIB.Also,endogenous(in situ)citrate was detected quantitatively to discriminate non-cancerous and PC mice,observed strong and lower(negligible)emission intensity on non-cancerous and cancerous prostate tissues,respectively.Because,the concentration of citrate is higher in healthy prostate compared with PC prostate.Furthermore,the analysis of sliced prostate tissues can give PC-related information for clinical diagnosis to prevent and treat PC in the initial stages.Therefore,we believe that the present probe is a promising biochemical reagent in diagnosing PC.