Reversible and Irreversible Chemisorption in Nonporous‐Crystalline Hybrids

Abstract

The tools of synthetic chemistry allow us to fine-tune the reactivity of molecules at a level of precision not yet accessible with inorganic solids. We have investigated hybrids that couple molecules to the superior thermal and mechanical properties of solids. Herein we present, to the best of our knowledge, the first demonstration of reactivity between hybrid perovskites and substrates. Reaction with iodine vapor results in a remarkable expansion of these materials (up to 36 % in volume) where new covalent CI bonds are formed with retention of crystallinity. These hybrids also show unusual examples of reversible chemisorption. Here, solid-state interactions extend the lifetime of molecules that cannot be isolated in solution. We have tuned the half-lives of the iodinated structures from 3 h to 3 days. These nonporous hybrids drive substrate capture and controlled release through chemical reactivity. We illustrate the strengths of the hybrid by considering radioactive iodine capture.

Decreasing the electronic confinement in layered perovskites through intercalation

“…24,25 During our experiments with I 2 chemisorption, we hypothesized that intercalation precedes halogenation of these nonporous solids. Here, the organic layers may stabilize I 2 incorporation similar to halogen solvation in organic liquids.…”

Thousand‐fold Conductivity Increase in 2D Perovskites by Polydiacetylene Incorporation and Doping

“…Alternatively, 1-N 2 can also be exposed to iodine vapors at room temperature to yield 1-N 2 /I 2 ,w hich also presents similar absorption and PXRD pattern to those of 1-O 2 and I-I 2 ( Figure S18 in the Supporting Information). Importantly,n either 1-I 2 or 1-N 2 /I 2 show evidence of iodine addition to triple or double bonds, [20] halide swap, [21] nor can the observed effects be explained by intercalation of I 2 . [22] Thespectroscopic similarities between 1-I 2 , 1-N 2 /I 2 ,and 1-O 2 suggest that partial oxidation of 1-N 2 is indeed responsible for the change in color.T ofurther confirm our hypothesis,we conducted solid-state X-band electron paramagnetic resonance (EPR) on samples of 1-as, 1-N 2 , 1-O 2 ,a nd 1-I 2 .E PR spectra of 1-as and 1-N 2 showed no signal whereas 1-O 2 and 1-I 2 showed as ignal at ag -value of 2.0033 and 2.0025, respectively (Figure 3a and S19 in the Supporting Information), both of which lie almost at the expected value for afree electron (2.0023) and clearly suggests the presence of an organic radical species within the material, which is most likely delocalized across the p-conjugated polydiacetylene.…”

Two‐Dimensional Halide Perovskites in Solar Cells: 2D or not 2D?

“…These interactions may include hydrogen and halogen bonds as well as p-p and van der Waalsi nteractions.W hile many of these interactions are weak,i nm ore complex organic moieties with multiple functional groups the effects of the interactions alongt he longitudinal axis of the organic molecule are additive and can, therefore, play ac rucial structure-directing role. [12] Importantly, the perovskite framework is highly tolerant of organic functional groups such as thiol, [13] carboxyl, [14] alkenyl, [15] alkynyl, [16] diyn, [17] and many others. [10,18,19] The tolerance for such aw ide varietyo fs izes and functional groups in the organic cations, along with the possibility to change the metal, halides, and thickness of the inorganic sheets (n value), make the possible 2D hybrid perovskites virtually infinite, and yeto nly af ew hundred perovskite structuresh ave been reported,a nd only a small fraction of those have been used in as olar cell.…”