Hydrogen-bonded Functional Materials Based On 1,8-naphtholactam:Design And Application

As a moderately strong intermolecular force,hydrogen bonding often plays a crucial role in molecular recognition and self-assembly.Hydrogen-bonded functional materials,assembled from elemental molecules via hydrogen bonding,have found widespread applications in various fields.However,the monotony of traditional hydrogen-bonding molecular structures and the singularity of their functions have limited the development of such materials.1,8-naphtholactam(Np),with its amide hydrogen-bonding group and outstanding fluorescence performance,is an ideal template molecule and excellent hydrogen-bonding carrier for constructing hydrogenbonding functional materials.This paper aims to synthesize and prepare hydrogenbonding functional materials with superior properties in the field by utilizing Np.Two main aspects of work are carried out:(1)making full use of its fluorescence performance and intrinsic amide hydrogen-bonding assistance to construct dual-state emission luminogens(DSEgens)with excellent luminescence efficiency and tunable spectra,and(2)utilizing Np’s intrinsic amide hydrogen-bonding equilibrium properties and fluorescence performance to act as a dual-functional hydrogen-bonding connection site in HOFs,constructing HOFs with gas separation and guest fluorescence response capabilities.Through precise structural design,detailed performance characterization,and application exploration,we fully demonstrate the inherent advantages of Np in hydrogen-bonding functional materials.The research results mainly include two aspects:1.Compared with traditional single-state luminescent materials such as ACQgens or AIEgens,DSEgens have more promising application prospects due to their high luminescence efficiency in both solid and solution states.In this study,Np was employed as a template molecule,and a series of visible-light full-spectrum emitting DSEgens were constructed by introducing different electron-donating groups onto its backbone.It was found that enhancing the electron-donating ability of the substituent group could increase the ICT effect and achieve red-shifted emission spectra.Importantly,the presence of substituent groups did not affect the hydrogen-bond-driven stacking mode in the crystal,thus enabling the efficient construction of full-spectrum DSEgens.The experimental results were supported by theoretical calculations,and the dyes at different concentrations exhibited excellent imaging performance for Hep G2 cells.2.Hydrogen-bonded organic frameworks(HOFs),pure organic porous materials assembled from small organic molecules via hydrogen bonding and other intermolecular interactions,are the focus of this study.By using the ligand molecule BC-4Np,which contains peripheral Np moieties and a central 9,9’-bicarbazole moiety,we successfully assembled a three-dimensional framework with dia topology,NCUHOF1.During the activation process to produce NCU-HOF1 a,we discovered a unique structural transformation behavior,which was studied in depth through monitoring of single-crystal-to-single-crystal transformation,providing important insights into the micro-mechanisms of phase transitions in the field of HOFs.Due to its high interpenetration degree of up to 11 and multiple π-π interactions within the crystal,NCU-HOF1 a exhibits remarkable stability.Benefitting from the Np-based luminescent hydrogen bonding site,the material exhibits excellent fluorescence properties.The electronic and spatial structural characteristics of the pores allow for efficient adsorption of ethylene while repelling ethane,exhibiting ultra-high ethylene/ethane selectivity.Additionally,the multiple interaction sites between the framework and ethylene are concentrated on the Np module,allowing for the presence of ethylene to restrict the non-radiative relaxation of Np,thus displaying a rare phenomenon of main body fluorescence enhancement.