# l‐Leucine‐Based Layered Coordination Polymer Supports for Immobilizing Basic Salts to Yield Solid CO2 Adsorbents Resistant to Moisture and Oxidation

## TL;DR

A new material made from amino acids can hold basic salts and capture CO2 efficiently even in humid and oxidative conditions.

## Contribution

A modular coordination polymer platform for immobilizing basic salts to create durable CO2 sorbents.

## Key findings

- Zn(Leu)2 supports diverse basic salts and maintains solid form under DAC conditions.
- CO2 uptake ranges from 0.17 to 1.04 mmol g−1 under relevant conditions.
- The sorbent retains CO2 capacity after oxidative aging, unlike conventional polyamine sorbents.

## Abstract

We demonstrate that amino acid‐based coordination polymers can serve as supports for a variety of basic salts. A layered framework, bis(l‐leucinato)zinc(II), Zn(Leu)2, prepared by an aqueous, base‐mediated procedure, provides crystallographically defined, carboxylato‐bridged two‐dimensional layered structures with intersheet surfaces. The interlayer spacing is molecularly tunable, and immobilizing potassium l‐leucinate increases the interlayer spacing in two discrete steps. Using this host, diverse basic salts can be immobilized to give solid sorbents that remain macroscopic solids under humid, DAC‐relevant conditions (400 ppm CO2, 293 K dew point, 313 K) while delivering equilibrium CO2 uptakes of 0.17–1.04 mmol g−1. After accelerated oxidative aging in simulated air (400 ppm CO2, 21% O2, 293 K dew point) at 393 K for 24 h, the amino acid‐based sorbent shows high retention in CO2 capacity, whereas a conventional polyamine‐based sorbent exhibits a marked decrease in the capacity. The combination of environmental durability and DAC‐relevant performance establishes Zn(Leu)2 as a general and modular platform for sustainable CO2 capture technologies.

A layered amino acid–based coordination polymer, (Zn(Leu)2), acts as a support that immobilizes diverse basic salts. The resulting solid sorbents remain nondeliquescent under humid, DAC‐relevant feeds while enabling CO2 capture. The interlayer‐immobilized sorbents exhibit high oxidative stability after accelerated oxidative aging, unlike conventional polyamine‐based solid sorbents.