Study On Synthesis,Assembly And Mechanochromism Of Naphthalene Derivatives

Naphthalene,as a rigid conjugated compound with multiple modification sites,processes excellent self-assembling performance,which affords it applications in various fields,such as chiral materials,mechanochromic matirials,fluorescent probes and liquids.However,most naphthalene assemblied systems have no chiral features,it is essential for achiral naphthalene derivatives to realize symmetry breaking and establish a relationship between molecular structure and symmetry breaking.On the other hand,most mechanochromic materials show red-shifted emission after exerting external mechanical force,which limits the developments and applications of mechanochromic materials.Thus,constructing mechanochromic materials with blue-shifted emission can better expand the mechanochromic applications and understand the assembly mechanisms.In this work,a naphthalene-based molecule with symmetry breaking property was synthesized to build a relationship between molecular structure and symmetry breaking.In addition,the mechanochromic blue-shifted material based on naphthalene derivative was also synthesized.This study reveals the relationship between molecular structure,assembly characteristic and material properties.The main points are as follows:1.For exploring the relationship between molecular structure and symmetry breaking,three molecules based on naphthalene were synthesized,and their assembling performance were further studied.Long fiber structures are obtained from N-1 and N-2,while N-3 simultaneously shows M-chirality and P-chirality helical fiber in methanol solution,indicating symmetry breaking occurred in N-3 assemblied system.This result demonstrates assembly process is closely dependent on molecular structure,which oridinates from different molecular interactions.The synergistic effect between hydrogen bonds and ?-? stacking are both essential for N-3 to form helical morphology.This study provides a theoretical basis for building relationship between molecular structure and symmetry breaking behavior.2.For obtaining a material with mechanochromic properties,a planar molecule N-MN with donor-acceptor structure was obtained based on N-1,which has good assembling property.N-MN has ICT and AIE properties in solution state.Moreover,N-MN shows a significant blue-shifted emission upon external mechanical force due to the change of molecular packing mode.This study enriches the molecular library of mechanochromic blue-shifted materials and helps us understand the relationship between emission properties and molecular structure deeply.