Rational Assembly of d¹⁰ Metal−Organic Frameworks with Helical Nanochannels Based on Flexible V-Shaped Ligand

Solvothermal reactions of Zn(II) or Cd(II) nitrates and V-shaped ligand of 4,4′-(hexafluoroisopropylidene)bis(benzoic acid) (H2hfipbb) in the presence or absence of 4,4′-bipy afforded four interesting d10 metal−organic frameworks with helical nanochannels, namely, Zn(hfipbb)·0.5H2O·0.5DMF enantiomers (P6222, 1a, and P6422, 1b), Zn(hfipbb)(4,4′-bipy)·DMF (2), and Cd(hfipbb)(DMF)·0.5DMF (3). The enantiomeric 1a and 1b exhibit similarly a (4,4)-connected 3D network with two types of helically 2-fold and 8-fold nanochannels along the c-axis, in which ultralong helical pitches are found in the 8-fold helical channels. Compound 2 features a 2D layered structure based on dizinc(II) paddle-wheel clusters with the appearance of left- and right-hand helical channels alternatively, while 1D double helical channels exist in the complicated structure of compound 3. The luminescent properties of all the compounds have also been studied.