Cationic induced assembly of two 2D zinc-terephthalate polymeric networks

Based on templates of Ph₃PCH₂Ph]Cl and Ph₄P]Cl (Ph₃PCH₂Ph] = benzyltriphenylphosphonium, Ph₄] = tetraphenylphosphonium), the hydrothermal reactions of zinc acetate dihydrate, H₂tp (tp = terephthalate) and water give rise to two new zinc-terephthalate coordination polymers, Ph₃PCH₂Ph]Zn(tp)Cl] (1) and Ph₄P]Zn(tp)(H₂O)₂·0.5tp] (2). X-ray single-crystal structural analysis reveals that both 1 (C₃₃H₂₆ClO₄PZn) and 2 (C₃₆H₃₀O₈PZn) crystallize in the 2D non-interpenetrating layered supramolecular networks with guest organophosphonium cations. Due to template effect of different guest cations, 1 presents an interesting 2D smectite-like lamellar framework that formed by the 4-linked (4,4) anionic zinc-terephthalate polymeric network and the interlayer Ph₃PCH₂Ph]⁺ exchangeable cations, while 2 shows a 2D 3-linked (6,3) H-bonded anionic zinc-terephthalate polymeric brickwall network with encapsulated guest Ph₄P]⁺ cations. Both compounds are stable up to about 300 °C, and exhibit intense fluorescent emission band at 446 nm (λ_exc = 328 nm) for 1 and 420 nm (λ_exc = 340 nm) for 2 in the solid state at room temperature.