Construction And Research Of Metallo Platinum(Ⅱ) Supramolecular Assemblies Driven By Multivalent Interactions

Supramolecular chemistry is a burgeoning science studying organized entities with higher complexity which are constructed by two or more chemical monomer units via non-covalent interactions. Supramolecular polymers, one kind of assemblies with polymeric properties, is a product of crosses and integration between supramolecular chemistry and polymer chemistry disciplines, which can be formed by self-assembly among designed monomer units driven by reversible and highly oriented non-covalent interactions. Construction of functional supramolecular polymers by means of various non-covalent interactions including hydrogen-bonding, metal-ligand interaction, host-guest recognition, electronic donor-acceptor interactions has increasingly become one promising research orientation in the polymer science. While design and preparation of novel building block as well as cooperative work of multivalent interactions would be indispensable for building well-ordered supramolecular polymeric systems with optics, electric, magnetism.In view of the special square planar geometries and unique optical properties of platinum(Ⅱ) acetylide unit, we, in this dissertation, introduce the concept of multivalent interactions into the research of metallo platinum(Ⅱ) supramolecular polymeric systems. Multivalent interactions including hydrogen-bonding, π-π stacking and metal-metal interactions between metallo platinum(Ⅱ) units are chosen as driven forces to achieve different series of metallic supramolecular assemblies (discrete and continuous). Our work primarily comprises two parts:In the first part, platinum(Ⅱ) acetylide unit with favourable rich optical properties is associated with molecular tweezers, which possess pre-organized conformation, to construct electron-deficient host molecules based on platinum(Ⅱ) terpyridyl acetylide pincers. Because of intramolecular NH…O hydrogen bonds in the skeleton units, the tweezer-like conformation of the host molecules are stabilized. Experimental results of UV-vis absorption and emission spectroscopy,1H NMR studies and ITC titration researches as well as DFT calculation confirm that molecular tweezer 2 exhibits moderate binding affinities towards the neutral guests, which are primarily driven by electron donor-acceptor and metal-metal interactions. Notably, molecular tweezer/guest complexation is liable to solvent polarity changes, mainly attributing to the cleavage of intramolecular hydrogen bonds on the tweezer receptor.In the second part, platinum(II) acetylide units with distinct substituent alkyl groups are served as building block to achieve a series of continuous platinum(II) acetylide supramolecular assemblies via the efficient coupling of amidic hydrogen bonds and π-π stacking interaction due to the cooperative and additional effect between multivalent interactions during self-assembling process. Test methods of concentration-depended’H NMR, temperature-depended UV-vis and CD experiments, on the one hand, demonstrate that the efficient cooperation of amidic hydrogen bonds and π-π stacking interaction could drive platinum(II) acetylide monomers to self-assemble into one-dimensional helical supramolecular polymers. On the other hand, compared with previously reported literatures, the conclusions reveal that regulating the relative position and cooperative effect between multivalent interactions could influence self-assemble process of monomer molecules. Moreover, self-assembling ability of monomer molecules could also be impacted by steric hindrance caused by its own substituent alkyl group. Larger substituent alkyl group could limit intermolecular regular arrangement, which is unfavourable for self-assembly.