Supramolecular Recognition And Selfassembly Of Cyclometalated Platimum(?) Complexes

Supramolecular chemistry represents the involvement via noncovalent bonds driven by hydrogen bonding,?-? interactions,metal coordination,charge transfer interaction,electrostatic attraction,host–guest recognition and so on.Such non-covalent interactions play crucial roles in controlling the structures and functions of the resulting assemblies,during the selfassembly process that produces new materials with new functions and various new morphology.Self-assembly has emerged as an excellent approach to create well-ordered supramolecular architectures with tunable properties,which underpin the role of solvent-directed or stimli-responsible approach.Organoplatinum(?)compounds have received enormous attention over the past decades due to their square-planar geometry as well as intriguing photo-physical properties.This dissertation,consisting 3 parts,focuses on the fabrication of novel supramoleculars based on Pt–Pt,?-?,and donor-acceptor charge-transfer interactions.Besides,self-assembly/disassembly triggered by pH or solvent have performed based on molecular tweezer/guest recognition motifs.In the first part,a novel star-shaped supramolecular amphiphile deriving from alkynylplatinum(?)terpyridine molecular tweezer/pyrene complexation has been designed and synthesized.Due to the implementing of intermolecular N–H…N hydrogen bond,the binding strength for the noncovalent linkages is significantly enhanced,together with amphiphilic structure,which favors for the formation of stable nano-spheres in aqueous solution.Moreover,self-assembly behaviors for the supramolecular amphiphile can be manipulated in a reversible manner,by taking advantage of the HFIP-responsive character of the fundamental molecular tweezer/guest recognition motif.The current system represents a novel and intriguing candidate for the construction of supramolecular amphiphile,which is promising for the further development of intelligent materials with desired functionalities.In the second part,studies of non-covalent host-guest association between alkynylplatinum(?)terpyridine molecular tweezer and organoplatinum(?)guests have been performed,which demonstrate p Hresponsive complexation behaviors.Complexation/decomplexation of noncovalent molecular tweezer/guest recognition motifs is highly reversible,due to the conformational transformation of the molecular tweezer receptor.Such transition can be directly monitored by the UV-vis absorption and emission spectral changes,upon successive addition of acid and base.In detail,the typical MMLCT bands disappear with the injection of acid,and restore to the original value upon addition of base.In sharp contrast,for the control molecular tweezer receptor without the presence of methoxy units on the spacer,pH-responsive spectroscopic changes are not obvious,indicating that methoxy units on molecular tweezer receptor play an important role for the complexation/decomplexation behaviors.The binding properties have been extensively studied by NMR experiments.Fundamentally,Pt···Pt,?-? and hydrogen bonding interactions have given to various spectroscopic changes depending on the structure of the guest molecules.The tweezering directed chemical switch in this system may be potential in controlled therapeutics delivery on pH modulation.In the third part,engineering of multi-component ?-conjugated molecules into well-ordered arrangement has aroused significant attention.The alternated arrangement,which is highly mimic for natural systems such as microtubule,shows promising prospects for photo-functional applications.In the third part,a novel supramolecular strategy has been developed,which is achieved via the embedment of metallophilic Pt···Pt and donor-acceptor charge transfer interactions between the heteromeric monomers.As a consequence,it demonstrates stronger binding affinities than the homomeric interactions,leading to the formation of supramolecular alternate coassembly.Due to the remarkable photo-physical signals,the resulting assemblies could serve as a benefit for the further development of supramolecular materials and the field of medicine.