What a difference a tail makes: 2D→2D parallel interpenetration of sheets to interpenetrated nbo networks using ditopic-4,2':6',4''-terpyridine ligands

Under conditions of crystal growth by layering at room temperature, 1,4-bis( n -hexoxy)-2,5-bis(4,2':6',4''-terpyridin-4'-yl)benzene ( 4 ) or 1,4-bis( n -decoxy)-2,5-bis(4,2':6',4''-terpyridin-4'-yl)benzene ( 5 ) reacts with ZnCl 2 to yield [Zn 2 Cl 4 ( 4 )] n or [Zn 2 Cl 4 ( 5 ) . 2MeOH] n . The compounds crystallize in the C 2/ c space group with 2-dimensional (4,4) nets which interpenetrate in a 2D®2D parallel manner. The ligands act as planar 4-connecting nodes linked through the zinc(II) centres. In contrast, 1,4-bis(3-phenylpropoxy)-2,5-bis(4,2':6',4''-terpyridin-4'-yl)benzene ( 6 ) reacts with ZnBr 2 to give [Zn 2 Br 4 ( 6 ) . H 2 O] n which crystallizes in the trigonal R –3 space group with a 3D assembly consisting of 2-fold interpenetrating nbo nets. Ligand 6 acts as a 4-connecting node and the zinc(II) centres are linkers. The pendant phenyl rings in 6 lie over the 4,2':6',4''-tpy domains in an adjacent net and the resulting close association of the interpenetrated nets leads to a highly porous network.