Design strategy for mechanochromic materials and investigating properties of water inside lyotropic liquid crystalline phases

Abstract

Stimuli responsive smart material has rapidly grown from few obscure examples to one of the most vibrant domain in the modern material science However material that responds to multiple stimuli integrating with mechanochromic vapochromic solvatochromic acidochromic and thermochromic behavior remains scarce for their unpredictable design principle Introduction of these diverse stimuli in a single luminogen requires discrete criteria of respective stimulus which ultimately makes them difficult to design Particularly in case of charge transfer luminogens the biggest challenge to construct the stimuli responsive mechanochromic material is the densely packed arrangement of luminogens in the solid state mostly as head to tail driven by the oppositely charged character in donor 8211 acceptor molecules owing to their well separated electron density The densely packed arrangements in the solid state suppress the possibility of mechanochromism as such packing is unable to produce metastable energy states under external mechanical force Therefore establishment of the structure property relationship based on charge transfer luminogens along with an inherent molecular level understanding of mechanochromism undoubtedly paves a new way to design this type of novel material On the other hand in case of centro symmetrically packed organic luminogens one important issue in the field of mechanochromism needs to address or solve and the issue is 8220 how to activate centrosymmetrically packed organic molecules Generally centrosymmetrically packed organic luminogens can 8217 t be activated under external mechanical force due to their zero gross dipole moment and degenerate electronic energy states in the solid state packing This severely limits the application of large number of centrosymmetrically packed organic luminogens in the development of stimuliresponsive mechanochromic materials thereby creating a barrier to apply the bulk amount of organic probes into the industrial or technological applications Keeping mind reg