The Construction Of Photogated Photoswitchable [2]Rotaxane And Nonequilibrium Hydrogen-bonded Supramolecular Polymers Based On The Naphthalene-Triazolinedione Photocycloaddition Reaction

Photoresponsive supramolecular assembly systems and materials with unique structural and functional spatiotemporal controllability can be constructed,through the introduction of appreciate photochromaphores into the molecular building blocks.In this thesis,by employing the recently developed green-light-driven photocycloaddition between naphthalene(NAP)and triazolidinedione(TAD)derivatives(the NAP-TAD adduct could be cycloreversed upon thermal relaxation in dark),unique photogated photoswitchable[2]rotaxane-based molecular shuttle and photoresponsive non-equilibrium hydrogen-bonsed supramolecular polymers are fabricated,which includes the following two aspects:In the part,a photoswitchable[2]rotaxane(R1)is designed and synthesized which consists of a cyclobis(paraquat-p-phenylene)(CBPQT⁴⁺)macrocycle interlocked by a dumbbell component containing three recognition sites including a photoswitchable azobenzene(AB)unit and a nonphotoactive biphenyl(BP)unit bridged by a naphthalene(NAP)unit.Detailed experimental investigations reveal that the UV(?=379 nm)/blue(?=440-450 nm)light irradiations can trigger the reversible Z/E photoisomerization of the AB unit on the thread of R1,and drive the shuttling motions of CBPQT⁴⁺macrocycle between the AB and BP/NAP units.This macrocyclic translational motion of R1 can be stopped by the generation of a steric energy barrier from a TAD-NAP cycloadduct on the axle center,upon irradiating the mixed solution of R1 and Bu-TAD additive with green light(?=520-525 nm).Moreover,the photodriven macrocyclic shuttling process of R1 could be conveniently restarted by the removal of the formed steric TAD-NAP cycloadduct upon thermal relaxation in dark.In this way,the“gated/open”states of the macrocyclic shuttling of R1 can be orthogonal controlled upon two independent photoactivated operations of UV/blue light irradiation and green light irradiation/thermal relaxation in dark.In the second part,two linear monomers are prepared including one(M1)modified with ureidopyrimidinone(UPy)and naphthalene(NAP)units,respectively,and the other(M2)equipped with two terminal UPy units linked by a NAP unit.It is found that M1 is capable of forming quadruple H-bonded dimer M1₂ in chloroform,while the M1₂and T1 are failed in the generation of linear supramolecular polymer upon green light(?=525 nm)irradiation.However,when the mixed solution of M2 and T1 is irradiated with green light,photocycloaddition reaction can be triggered between the TAD units of T1 and the NAP units in the main chain of H-bonded supramolecular polymer(SP2)formed from M2.This leads to the generation of cross-linked H-bonded supramolecular polymeric network(SPN3),which can be reversely conversed to the linear H-bonded supramolecular polymer after the NAP-TAD cycloadducts of the linkage undergo cyclo-reversion upon standing in dark.