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Chiral Supramolecular Frameworks Based on Chiral Metallocycles: Crystal Structures and Photophysical Properties
Author(s) -
Xu Jinxia,
Wang Ruiying,
Li Yameng,
Gao Zhiyang,
Yao Rui,
Wang Song,
Wu Benlai
Publication year - 2012
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201200100
Subject(s) - chemistry , supramolecular chemistry , chirality (physics) , crystallography , ligand (biochemistry) , titration , stereochemistry , crystal structure , receptor , biochemistry , chiral symmetry breaking , physics , quantum mechanics , nambu–jona lasinio model , quark
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 (H 2 ptpy). The resulting compounds 1 – 4 , namely [Cd 2 (Hptpy) 2 (Ac) 2 ] · 3CH 3 OH · H 2 O ( 1 ) [Ni 2 (Hptpy) 2 (CH 3 OH)(H 2 O)](ClO 4 ) 2 · CH 3 OH · H 2 O ( 2 ), [Ni 2 (Hptpy) 2 (H 2 O) 2 ](SCN) 2 ( 3 ), and [Cu 2 (Hptpy) 2 ](dca) 2 · 4H 2 O ( 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 [Cd 2 (Hptpy) 2 ] 2+ (log β = 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 H 2 ptpy 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.