Iodine Release and Recovery, Influence of Polyiodide Anions on Electrical Conductivity and Nonlinear Optical Activity in an Interdigitated and Interpenetrated Bipillared-Bilayer Metal-Organic Framework

{[Cu-6(pybz)(8)(OH)(2)]center dot I-5(-)center dot I-7(-)}(n). (1), obtained hydrothermally by using iodine molecules as a versatile precursor template, consists of a cationic framework with two types of zigzag channels, which segregate I-5(-) and I-7(-) anions. The framework exhibits the first observed bipillared-bilayer structure featuring both interdigitation and interpenetration. 1 displays high framework stability in both acidic (HCl) and alkaline (NaOH) solutions. 1 slowly releases iodine in dry methanol to give [Cu-6(pybz)(8)(OH)(2)](I-)(2)center dot 3.5CH(3)OH (1') and partially recovers iodine from cyclohexane to form [Cu-6(pybz)(8)(OH)(2)](I-)(2)center dot xI(2) (1 ''). Differences of up to 100 times in electrical conductivity and of 4 times in nonlinear optical activity (NLO) have been measured between 1 and 1'. This compound is one of few displaying multifunctionality, electrical conductivity, NLO, and crystal-crystal stability upon release and recovery of iodine. It is also unique in the iodine release from polyiodide anions in a metal-organic framework.