Unusual phosphorescence of boric acid:From impurity or clusterization-triggered emission?

The unusual room-temperature phosphorescence(RTP)from the n electron-rich systems(without regular conjugated structure)has aroused great attention for structural designing and application development of RTP materials.Such emission has been ascribed to clusterization-triggered emission(CTE)via weak through-space conjugation of n electrons in the heteroatoms.However,there was suspicion on such RTP as impurity-induced result.Therefore,in-depth photophysical investigation and effective proof methods are needed to trace the origin of such RTP.Here,using the recently reported CTE phosphor boric acid as the example,a Jablonski diagram-based verification protocol was proposed to confirm the intrinsic luminescence of the n electrons-rich systems.Meanwhile,some other types of luminophores,that is,traditional phosphors,already reported impurity-induced and host-guest doping luminophores,were included for comparison.Overall,this work provides a basic paradigm for differentiating between the impurity-involved and the n electron-rich phosphors and will further deepen the understanding of nonconventional luminescence.

Manipulating noncovalent conformational lock via side-chain engineering for luminescence at aggregate level

The unfavorable photochemical processes at the molecular level have become a bar-rier limiting the use of aromatic amides as high-performance luminescent materials.Herein,we propose a reliable strategy for manipulating noncovalent conformational lock(NCL)via side-chain engineering to burst out eye-catching luminescence at the aggregate level.Contrary to the invisible emission in dilute solutions,dyad OO with a three-centered H-bond gave the wondrous crystallization-induced emis-sion with a quantum yield of 66.8%and clusterization-triggered emission,which were much brighter than those of isomers.Theoretical calculations demonstrate that crystallization-induced planarized intramolecular charge transfer(PICT),con-formation rigidification,and through-space conjugation(TSC)are responsible for aggregate-state luminescence.Robust NCL composed of intramolecular N-H⋅⋅⋅Ointeractions could boost molecular rigidity and planarity,thus greatly facilitating PICT and TSC.This study would inspire researchers to design efficient luminescent materials at the aggregate level via rational conformational control.

A clusteroluminescent supramolecular polymer network constructed by pillararene and its application in information encryption

Clusterization-triggered emissive(CTE)materials have attracted great attention in recent years.The regulation of the emission property of materials with CTE property through supramolecular interactions is an excellent strategy for the construction of smartfluorescent materials.In this work,we have pre-pared a regulatable supramolecular polymer network with CTE properties through pillararene-based host-guest interactions.The pillar[5]arene-grafted poly(methyl methacrylate)(PMMA)showed a classic CTE character.After adding Brooker’s merocyanine-grafted polymer to the solution of the pillar[5]arene-containing PMMA,the supramolecular polymer network gel formed by the host-guest inter-actions between pillararene and Brooker’s merocyanine guest.This supramolecular network showed brighterfluorescence than the pillar[5]arene-grafted PMMA in the solid state.In addition,thefluorescence emission of the supramolecular network can be further regulated by pH conditions.After adding an acid,the Brooker’s merocyanine-containing guest polymer was protonated,and the supramolecular net-work changed to a protonated network through host-guest interactions between protonated Brooker’s merocyanine guest and pillararene.Interestingly,thefluores-cence was quenched when the supramolecular network turned into the protonated network.After adding a base,the protonated network can convert back to the origi-nal network,along with recovery of thefluorescence.Therefore,the regulation of thefluorescence of the supramolecular polymer materials with CTE was successfully realized by pillararene-based host-guest interactions.Furthermore,this tailorablefluorescent supramolecular polymer network system was applied as an information encryption material.

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.

Catalyst-Free Four-Component Spiropolymerization for the Construction of Spirocopolymers with Tunable Photophysical Properties

Spiropolymers have gained a great deal of interest from both academic and industrial fields by virtue of their unique geometric structures and physical properties.Herein,we prepared a series of spirocopolymers through the catalyst-free four-component spiropolymerization of diisocyanides,activated alkynes,and two different kinds of monomers with reactive carbonyl groups.It is found that the polymerization reactivity of monomers,feeding modes,and feed ratios play significant roles in spirocopolymerization.Monomers with high reactivity and feeding reactive monomers first contribute to improving the molecular weights and yields of the polymers.The constructed copolymers have two different kinds of spiro structures,which is confirmed by the nuclear magnetic resonance.In addition,the spirocopolymers display the unique cluster-triggered emission and aggregation-induced emission properties,and their emission properties can be well-modulated by altering the ratio of comonomers.It is highly anticipated that this line of research will enrich the methodology of multi-component spiropolymerization,and provide a new insight into developing spiropolymers with various spiro structures and tunable properties.