Turning Non-Emissive Schiff Bases Into Aggregate Emitters

Schiff bases are a crucial component in various functional materials but often exhibit non-emissive behavior which significantly limits their potential applications as luminescent materials. However, traditional approaches to convert them into aggregate emitters often require intricate molecular design, tedious synthesis, and significant time and resource consumption. Herein, we present a cocrystallization-induced emission strategy that can transform non-emissive (hetero)aryl-substituted Schiff bases into green-yellow to yellow aggregate emitters via even simple grinding of a mixture of Schiff bases and 1,2,4,5-tetracyanobenzene (TCB) mixtures. The combined experimental and theoretical analysis revealed that the cocrystallization inhibits the C=N isomerization and promotes face-to-face π-π interaction, which restricts access to both the dark state and canonical intersection to ultimately induce emission. Furthermore, the induced emission enables the observation of solid-state molecular diffusion through fluorescence signals, advancing white light emission diodes, and notably, solution-processed organic light-emitting diodes based on cocrystal for the first time. This study not only highlights the potential of developing new C=N structural motifs for AIEgens but also could boost advancements in related structure motifs like C=C and N=N.

Synthesis of natural product hybrids by the Ugi reaction in complex media containing plant extracts

Plant extracts are rich in a wide variety of molecules with diverse biological activities. Chemical engineering of plant extracts has provided a straightforward and simultaneous synthetic route for artificial molecules derived from plant products. This study achieved the synthesis of 13 natural product-like molecules by the Ugi multicomponent reaction using plant extracts as substrates. In particular, the engineering of a mixture of plant extracts demonstrated a unique synthetic route to a series of natural product hybrids, whereby otherwise unencountered naturally occurring molecules of different origins were chemically hybridized in complex media. Even though these reactions took place in complex media containing plant extracts, the well-designed process achieved a good conversion efficiency (~ 60%), chemoselectivity, and reproducibility. Additionally, some of the Ugi adducts exhibited promising inhibitory activity toward protease.

Probing the supramolecular features via π–π interaction of a di-iminopyrene-di-benzo-18-crown-6-ether compound: experimental and theoretical study

Herein, we report the formation of a potential supramolecular arrangement mediated by inter- and intra-molecular interactions between di-iminopyrene-dibenzo-18-crown-6-ether molecules.

Facile Synthesis of an Organic Solid State Near-Infrared-Emitter with Large Stokes Shift via Excited-State Intramolecular Proton Transfer

An organic solid-state near-infrared (NIR)-emitter (λ_em = 738 nm) exhibiting large Stokes shift (Δλ = 293 nm) through the excited-state intramolecular proton transfer phenomenon has been synthesized and characterized. The present discovery points to the possibility of achieving a new family of solid-state NIR emitters starting from simple aldehyde and amine precursors.

A Single Crystal with Multiple Functions of Optical Waveguide, Aggregation-Induced Emission, and Mechanochromism

A novel single crystal, PyB, is produced in a high yield by the simple method of connecting a pyrene unit and a rhodamine B moiety together. PyB shows multiple functions of aggregation-induced emission, low-loss optical waveguiding, and tricolored mechanochromism. The crucial point for fabricating such a multifunctional single crystal is selecting the C═N group as a spacer, which simplifies the synthetic procedure, confines the molecular conformation to develop single crystals, and allows one to dynamically observe the color variation in situ and quantitatively analyze the effect of applied pressures. Such a simple approach may be extended to other fluorophores, thus providing a new opportunity for the real world application of mechanochromic materials for mechanical sensors, optical encoding, and optoelectronic devices, etc.

A chemosensor for micro- to nano-molar detection of Ag+ and Hg2+ ions in pure aqueous media and its applications in cell imaging

The synthesis and characterization of a simple thiourea-based Ag⁺ and Hg²⁺ sensor is reported.

Modulating sensitivity and detection mechanism with spacer length: a new series of fluorescent turn on chemodosimeters for Pb2+ based on rhodamine–quinoline conjugates

A series of highly selective and sensitive fluorescent turn on chemodosimeters and a chemosensor have been developed for Pb²⁺ ions based on rhodamine–quinoline conjugates.

A sandwich-type zinc complex from a rhodamine dye based ligand: a potential fluorescent chemosensor for acetate in human blood plasma and a molecular logic gate with INHIBIT function

Zn-R1 exhibits reversible binding with acetate yielding different optical and fluorescence outputs on alternate addition of zinc and acetate ions.

Self-assembled material of palladium nanoparticles and a thiacalix[4]arene Cd(ii) complex as an efficient catalyst for nitro-phenol reduction

A cadmium complex based on the thiacalix[4]arene scaffold is utilized to synthesize a material with palladium nanoparticles, which behaves as an efficient catalyst for the conversion of 4-nitrophenol to 4-aminophenol.

Lysine triggered ratiometric conversion of dynamic to static excimer of a pyrene derivative: aggregation-induced emission, nanomolar detection and human breast cancer cell (MCF7) imaging

Dynamic to static excimer formation followed by lysine concentration dependent spectral shift of a single crystal X-ray structurally characterized pyrene based probe allows highly selective ratiometric detection of lysine at the nanomolar level.

A uracil nitroso amine based colorimetric sensor for the detection of Cu2+ions from aqueous environment and its practical applications

Uracil nitroso amine based colorimetric chemosensor for Cu²⁺ions from a 100% aqueous environment.

Dansyl-carbazole AIEE material for selective recognition of thiourea derivatives

New dansyl-carbazole based compound 3 is designed and synthesized, which exhibits aggregation induced emission enhancement (AIEE) behaviour in H₂O : THF (60 : 40, v/v). Aggregates of compound 3 in H₂O : THF (60 : 40, v/v) selectively recognize thiourea motifs over urea motifs.

A remarkable effect of N,N-diethylamino functionality on the optoelectronic properties of a salicylimine-based probe for Al(3+)

A new live-cell permeable, fluorescent probe comprised of a simple salicylimine-based Schiff base (SA1) has been developed for Al3+ with nano-molar sensitivity in aqueous media. SA1 was synthesized through a simple structural modification of a recently reported receptor SA2 by the incorporation of the N,Ndiethylamino (DEA) group as a fine controllable unit. This modification affects the performance of SA1 remarkably in terms of its sensitivity, water compatibility and efficiency as well as its mechanistic aspect. The presence of the DEA group in SA1 led to its dual channel emission due to the TICT state and at the same time its hydrophobic nature was also responsible for controlling the strong hydration of Al3+ ions in aqueous media which ultimately led to the high sensitivity of SA1 for Al3+. The structure of SA1 was confirmed by single crystal X-ray diffraction and its binding with Al3+ was studied in detail using UVvisible, fluorescence and 1H NMR spectral studies along with mass determination. The effort of getting a single crystal of Al3+–SA1 led to single crystals of Cl−/NO3 − complexes of protonated SA1 which were fully characterized by their XRD studies.

Imatinib intermediate as a two in one dual channel sensor for the recognition of Cu2+and I−ions in aqueous media and its practical applications

An imatinib intermediate was developed for the colorimetric sensing of Cu²⁺ions in aqueous solution.

New triangular steroid-based A(LS)3 type gelators for selective fluoride sensing application

A new series of triangular steroid-based A(LS)₃ type gelators has been developed which exhibited selective fluoride sensing abilities. The gelation, self-assembly and anion sensing properties of these gelators could be controlled by systematically altering their molecular structures.