Efficient and pH-Sensitive Nonconventional Luminescent Polymers for Cellular Imaging and Ion Detection

Nonconventional luminescent materials(NLMs)are a type of organic luminescent materials that does not contain aromatic units.Due to the simplicity of the synthesis process,mild reaction conditions,good hydrophilicity and biological compatibility,NLMs have attracted much attention.Nevertheless,numerous reports indicate that NLMs can only effectively luminesce at high concentrations and in solid state,which limits their applicability in the field of cell imaging.This study addresses this limitation by designing and synthesizing oligomers P1,P2 and P3 using ethylene glycol diglycidyl ether and amine compounds containing ethylene groups.These oligomers exhibit remarkable luminescence efficiency reaching as high as 9.2%in dilute solutions(0.1 mg/m L),making them among the best NLMs in this category.Furthermore,the synthesized oligomers exhibit excitation wavelength-dependent and concentration-dependent luminescence intensity,fluorescence response to temperature and p H changes,as well as the ability to identify Fe^(3+),Cu^(2+)and Mo^(5+)in dilute solutions.These characteristics render them potentially useful in the for cell imaging.

Clustering-triggered Emission of Cellulose and Its Derivatives

In recent years, nonconventional luminogens free of aromatic groups have attracted extensive attention due to their academic importance and promising wide applications. Whilst previous studies generally focused on fluorescence from aliphatic amine or carbonylcontaining systems, less attention has been paid to room temperature phosphorescence(RTP) and the systems with predominant oxygen functionalities. In this work, photophysical properties of the polyhydroxy polymers, including microcrystalline cellulose(MCC), 2-hydroxyethyl cellulose(HEC), hydroxypropyl cellulose(HPC), and cellulose acetate(CA), were studied and compared. While MCC,HEC, and HPC solids showed bright emission alongside distinct RTP, CA demonstrated relatively low intensity of solid emission without noticeable RTP. Their emissions were explained in terms of the clustering-triggered emission(CTE) mechanism and conformation rigidification. Additionally, on account of its intrinsic emission, concentrated HEC aqueous solution could be used as the probe for the detection of 2,4,6-trinitrophenol(TNP).

Crystallization-induced phosphorescence of pure organic luminogens

This review summarizes the recent progress of efficient room temperature phosphorescence（RTP） from pure organic luminogens achieved by crystallization-induced phosphorescence（CIP）,with focus on the advances in our group.Besides homocrystals,mixed crystals and cocrystals are also discussed.Meanwhile,intriguing RTP emission from the luminogens without conventional chromophores is demonstrated.

A gelable pure organic luminogen with fluorescence-phosphorescence dual emission

Pure organic luminogens with room temperature phosphorescence(RTP) have drawn much attention due to their fundamental importance and promising applications in optoelectronic devices, bioimaging, sensing, etc. Fluorescence-phosphorescence dual emission at room temperature, however, is rarely observed in pure organic materials. Herein, we reported a metal-and heavy-atom free pure organic luminogen with tert-butyl groups, DtBuCZBP, which is ready to form organogels in dimethylsulfoxide(DMSO).It emits prompt and delayed fluorescence, as well as RTP, namely dual emission in as-prepared solid, gels and polymeric films.To the best of our knowledge, it is the first example of metal-and heavy-atom free pure organic gelator with RTP emission. Such unique RTP and moreover dual emission properties in different states make DtBuCZBP a potential material for diverse applications.

Aggregation-induced Emission of Non-conjugated Poly(amido amine)s:Discovering,Luminescent Mechanism Understanding and Bioapplication

It is found that the fluorescence of aliphatic poly（amido amine）s including linear and hyperbranched ones can be dramatically enhanced by simple aggregation of polymer chains, attributing to the formation of a variety of intra- and interchain clusters with shared lone-pair electrons and the restriction of intramolecular motions. Thanks to the combination of strong solid fluorescence and excellent biocompatibility, these non-conjugated polymers become promising candidates for bioimaging such as bacterial detection. This finding not only extends the aggregation-induced emission（AIE） systems from conjugated compounds to non-conjugated materials, which expands the bioapplication range of AIE systems, but also sheds light on the exploration of novel unconventional luminogens.

Clusteroluminescence:A gauge of molecular interaction

Clusteroluminescence(CL)materials,as an emerging class of luminescent materials with unique photophysical properties,have received increasing attention owing to their great theoretical significance and potential for biological applications.Although much progress has been made in the design,synthesis and application of CL materials,there is still a big challenge in the emission mechanism.So far,throughspace interaction has been proposed as the preliminary mechanism of the corresponding clusterizationtriggered emission(CTE)effect,but a systematic theory is still needed.This review summarizes the current mechanistic understanding of CL materials including organic/inorganic small molecules,and polymers with/without isolated aromatic structures.In addition,some strategies to achieve high quantum yield,adjustable emission color,and persistent room temperature phosphorescence in CL materials are also summarized.At last,a perspective of the mechanism and application of CL materials are demonstrated,which inspire the researchers working on the development of new kinds of functional materials.

Aggregation-induced phosphorescence and mechanochromic luminescence of a tetraphenylethene-based gold(Ⅰ) isocyanide complex

In this study,a new twisting gold（Ⅰ） isocyanide complex based on tetraphenylethene（TPE）,TPE-NC-Au.was designed and synthesized.It exhibits aggregation induced phosphorescence（AIP） characteristics,owing to the incorporation of Au moiety and conformation rigidification in the aggregated states.Moreover,the emission color of the crystalline solid of TPE-NC-Au changes from blue（454 nm） to green（500 nm） in response to mechanical grinding,due to the combined effects of conformation planarization,enhanced π…π stacking,as well as the emergence of aurophilic interactions in the ground amorphous state.Notably,the emission color can be restored upon solvent fuming,associating with the reconstruction of crystalline lattices.The AIP and switchable mechanochromism of TPE-NC-Au make it suitable for potential applications in bioimaging,sensing,and optoelectronic devices.

Polymorphism dependent triplet-involved emissions of a pure organic luminogen

Polymorphism has been frequently used in tuning the singlet emissions of pure organic dyes. The modulation of triplet-involved emissions, particularly room temperature phosphorescence(RTP),however, is scarcely reported. Herein, polymorphism is reported to tune the triplet-involved emissions of 2 CZBZL, a newly designed pure organic luminogen consisting of twisted benzil and two planar carbazole moieties. Other than the conventional modulation through changing molecular conformation and packing, vibration can also finely tune the triplet-involved emissions. Besides prompt fluorescence(PF),polymorph B with relatively extended conformation emits thermally activated delayed fluorescence(TADF), whereas the others(A, C–E) with similarly more twisted conformations generate predominant RTP or simultaneous DF and RTP. These results demonstrate the fascinating chance to regulate the tripletinvolved emissions through controlling conformation and vibration.