Reversible iodine absorption by alkali-TCNQ salts with associated changes in physical properties

Abstract

Alkali metal salts of 7,7′,8,8′-tetracyanoquinodimetane (TCNQ) reversibly absorb iodine forming the ternary salts M(TCNQ)I (M = Li, Na, K) and M 2 (TCNQ) 3 I 2 (M = Rb). The ternary salts are also obtained by solid-state reactions of TCNQ with alkali iodides. These salts are paramagnetic and have high electrical conductivities, ~10-1 S cm-1 for compacted pellets, whereas the alkali metal salts of TCNQ are diamagnetic insulators. The ternary salts further absorb iodine to give over-doped salts M(TCNQ)I n (n ~ 6, M = Na, K), which gradually release iodine to give M(TCNQ)I. In contrast, the solid-state reaction of F 4 TCNQ and sodium iodide produces Na(F 4 TCNQ), which does not exhibit iodine absorption.

Reversible and Irreversible Chemisorption in Nonporous‐Crystalline Hybrids

“…Typically, sorbents capture gases through reversible physisorption. [1] However, chemisorption of iodine by nonporous solids to form polyiodides [22] and doped chargetransfer salts [23] have been reported. The reversible iodination of alkene molecules in hybrid perovskites is an intriguing example of gas capture through reversible chemisorption where the equilibrium for iodine release can be tuned through molecular design.…”

Reversible iodine absorption of nonporous coordination polymer Cu(TCNQ)

“…This contrasts with the results of the reaction of alkali iodides, which produces M(TCNQ)I by grinding with TCNQ. 5 Annealing of Cu(TCNQ)I 4 obtained by the grinding reaction produced Cu(TCNQ) with the XRD pattern of phase II.…”

Reversible and Irreversible Chemisorption in Nonporous‐Crystalline Hybrids

“…[1] However, chemisorption of iodine by nonporous solids to form polyiodides [22] and doped chargetransfer salts [23] have been reported. [1] However, chemisorption of iodine by nonporous solids to form polyiodides [22] and doped chargetransfer salts [23] have been reported.…”