Two kinds of coumarin substituted diacetylene monomers

named as CODA and CO2DA

were designed and synthesized.The effect of the flexible spacer on their interfacial behavior

photo-polymerization of their resulting LB films and the chirality formation of polydiacetylene (PDA) backbone was investigated and discussed in detail.LB films of coumarin substituted diacetylene monomer could be prepared at 35 mN/m on water subphase through LB technique.Although the above CODA monomers were achiral

the CODA LB films exhibited obvious CD signal

which should be ascribed to the overcrowded packing of coumarin units upon compression.As for CO2DA sample

no obvious CD signal could be observed.Strong collective noncovalent interaction (- stacking) was believed to be responsible for the formation of the chiral supramolecular assemblies.When exposed to UV irradiation with 254 nm light

LB films derived from CODA could be polymerized into blue phase and yield obvious chirality for PDA chain although CODA monomer was achiral.However

no obvious CD signal could be observed for the films derived from CO2DA PDA backbone.It was demonstrated that the intermolecular irregular arrangement of the coumarin groups in the LB films was not favorable for the topo-polymerization and chirality formation of PDA backbone.