The supramolecular isomerism based on argentophilic interactions: the construction of helical chains with defined right-handed and left-handed helicity.
The reactions of racemic and enantiopure macrocyclic compounds [Ni(alpha-rac-L)](ClO(4))(2) (containing equal amounts of SS and RR enantiomers), [Ni(alpha-SS-L)](ClO(4))(2), and [Ni(alpha-RR-L)](ClO(4))(2) with K[Ag(CN)(2)] in acetonitrile/water afford three 1D helical chains of {[Ni(f-rac-L)][Ag(CN)(2)](2)}(n) (1), {[Ni(f-SS-L)](2)[Ag(CN)(2)](4)}(n) (Delta-2), and {[Ni(f-RR-L)](2)[Ag(CN)(2)](4)}(n) (Lambda-2); one dimer of [Ni(f-rac-L)][Ag(CN)(2)](2) (3); and one trimer of [Ni(f-rac-L)Ag(CN)(2)](3).(ClO(4))(3) (4) (L = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane). Compounds 1, Delta-2, Lambda-2, and 3, which are supramolecular isomers, are constructed via argentophilic interactions. In 1, [Ni(f-RR-L)][Ag(CN)(2)](2) enantiomers alternately connect with [Ni(f-SS-L)][Ag(CN)(2)](2) enantiomers through intermolecular argentophilic interactions to form a 1D meso-helical chain, and the 1D chains are further connected through the interchain hydrogen bonds to generate a 2D network. When chiral [Ni(alpha-SS-L)](ClO(4))(2) and [Ni(alpha-RR-L)](ClO(4))(2) were used as building blocks, two supramolecular stereoisomers of Delta-2 and Lambda-2 were obtained, which show the motif of homochiral right-handed and left-handed helical chains, respectively, and the 1D homochiral helical chains are linked by the interchain hydrogen bonds to form a 3D structure. In 3, a pair of enantiomers of [Ni(f-RR-L)][Ag(CN)(2)](2) and [Ni(f-SS-L)][Ag(CN)(2)](2) connect with each other through intermolecular argentophilic interactions to form a dimer. The reaction of [Ni(alpha-rac-L)](ClO(4))(2) with K[Ag(CN)(2)] in acetonitrile gives a trimer of 4; each trimer is chiral with unsymmetrical RR, RR, and SS, or RR, SS, and SS configurations. The homochiral nature of Delta-2 and Lambda-2 was confirmed by the results of solid circular dichroism spectra measurements. The solid samples of 1-4 show strong fluorescent emissions at room temperature.
Zheng
Xiao-Dan
XD
MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, State Key Laboratory of Optoelectronic Materials and Technologies, and School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, China.
Jiang
Long
L
Feng
Xiao-Long
XL
Lu
Tong-Bu
TB
D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D008163:Luminescent Measurements; D009532:Nickel / Q000737:chemistry; D009942:Organometallic Compounds / Q000737:chemistry*; D012834:Silver / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013237:Stereoisomerism
D009942:Organometallic Compounds; D012997:Solvents; D012834:Silver; D009532:Nickel