1401959-61-2Relevant academic research and scientific papers
Chiral supramolecular frameworks based on chiral metallocycles: Crystal structures and photophysical properties
Xu, Jinxia,Wang, Ruiying,Li, Yameng,Gao, Zhiyang,Yao, Rui,Wang, Song,Wu, Benlai
, p. 3349 - 3360 (2012)
Four purely chiral supramolecular frameworks were constructed from a new chiral terpyridyl ligand, (S)-2{4-[2,6-bis(pyridin-2-yl)pyridin-4-yl] benzylamino}propanoic acid (H2ptpy). The resulting compounds 1-4, namely [Cd2(Hptpy)2(Ac)2]?3CH 3OH?H2O (1) [Ni2(Hptpy) 2(CH3OH)(H2O)](ClO4) 2?CH3OH?H2O (2), [Ni 2(Hptpy)2(H2O)2](SCN)2 (3), and [Cu2(Hptpy)2](dca)2?4H 2O (4) (Ac = acetate and dca = dicyanamide) all consist of those chiral metallocyclic units. As expected, those chiral nanometallocycles not only induced a chiral array or helicates but also amplified chirality through hydrogen-bonding interactions, and finally aggregated into complicated higher-dimensional chiral supramolecular architectures with chiral voids for further use. The formation of the metallocyclic units is easily monitored by UV/Vis spectra. Spectrophotometric titrations were performed by titrating Na(Hptpy) with a soltution of Cd(Ac)2 in methanol, and the global stability constants of [Cd2(Hptpy)2]2+ (logβ = 17.60) were calculated. In combination with the structural analyses and UV/Vis and ES mass spectra, it is tentatively deduced that metallocycle units in 1-4 are the thermodynamically favored species in solution. Both the chiral H2ptpy ligand and 1 in the solid state and in solution display purple emission. The bathochromic shift of 1 is mainly due to the bichelation and intrametallocyclic π-π interactions. By the self-assembly of the synthesized purely chiral terpyridyl ligand (S)-2{4-[2,6-bis(pyridin-2-yl) pyridin-4-yl]benzylamino}propanoic acid (H2ptpy) with metal ions, a new class of purely chiral metal-organic frameworks built from the chiral metallocyclic subunits formed by two chiral (Hptpy)- anions that bridge two metal ions in a head-to-tail style was prepared and characterized.
