Syntheses, Characterizations, Luminescent Properties, and Controlling Interpenetration of Five Metal–Organic Frameworks Based on Bis(4-(pyridine-4-yl)phenyl)amine

Five
new metal–organic frameworks (MOFs), {[Zn2(BPPA)2­(BDC)2]­·6H2O}n (1), {[Cd3(BPPA)­(BDC)2­(DMF)2]­·DMF­·3H2O}n (2), {[Zn­(BPPA)­(NDC)1/2­(HCO2)]}n (3), {[Zn3(BPPA)3­(TFBDC)3]­·H2O}n (4), and {[Cd2(BPPA)2­(TFBDC)2]}n (5), have been
synthesized from the self-assembly of the “V-shape”
BPPA ligand with Zn/Cd metal salts, incorporating coligands (H2BDC = 1,4-benzenedicarboxylic acid, H2NDC = 2,6-naphthalenedicarboxylic
acid, TFBDC = 2,3,5,6-tetrafluoroterephthalic acid, BPPA = bis­(4-(pyridine-4-yl)­phenyl)­amine,
DMF = N,N-dimethylformamide). Compound 1 is a 4-fold interpenetrated three-dimensional (3D) network
with sra topology. Compound 2 is the first
2-fold interpenetrated sxa topology, which is reported
only non-interpenetration before. Compound 3 is a one-dimensional
chain by utilizing a “longer” rigid H2NDC
coligand. Via a “fatter” rigid TFBDC ligand, we control
interpenetration by one-pot synthesis. Both compounds 4 and 5 are non-interpenetrated 3D 6T8 frameworks,
and the 6T8 topology has rarely been reported in MOFs
before. Interestingly, carboxyl groups in 1–5 adopt various coordinate modes. Luminescent properties of 1–5 have also been explored, and the emission
decay lifetimes of 4 and 5 are longer than
compounds 1–3 and free ligands because
of a fluorescent synergistic effect. This may provide an feasible way to exploit materials with
long emission decay lifetimes.