NO as a Reagent for Topochemical Framework Transformation and Controlled Nitric Oxide Release in Covalent Organic Frameworks

Abstract

Covalent organic frameworks (COFs) have emerged as versatile platforms for the separation and storage of hazardous gases. Simultaneously, the synthetic toolbox to tackle the “COF trilemma” has been diversified to include topochemical linkage transformations and post-synthetic stabilization strategies. Herein, we converge these themes and reveal the unique potential of NO as a new reagent for the scalable gas-phase transformation of COFs. Using physisorption and solid-state nuclear magnetic resonance spectroscopy on 15N-enriched COFs, we study the gas uptake capacity and selectivity of NO adsorption and unravel the interactions of NO with COFs. Our study reveals the clean deamination of terminal amine groups on the particle surfaces by NO, exemplifying a unique surface passivation strategy for COFs. We further describe the formation of a NONOate-linkage by the reaction of NO with an amine-linked COF, which shows controlled release of NO under physiological conditions. NONOate-COFs thus show promise as tunable NO delivery platforms for bioregulatory NO release in biomedical applications.

A Multifunctional Covalent Organic Framework Nanozyme for Promoting Ferroptotic Radiotherapy against Esophageal Cancer

“…Further evidence of successful imine bond formation and Fc modification was provided by 13 C cross-polarization−magic angle spinning nuclear magnetic resonance (CP-MAS NMR) spectra (Figure 2D). The peaks at 157 and 99 ppm unambiguously identified the presence of the carbon atoms in the C�N and C−I functional groups, 57 whereas the peak at 72 ppm was associated with the Fc groups. 58 In addition, a moderately intense band at 1616 cm −1 , attributable to the C� N stretching vibration, in the attenuated total reflection− Fourier transform infrared (ATR−FTIR) spectrum was observed, supporting our conclusion that imine-linked COFs has been successfully synthesized (Figure 2E).…”

Covalent organic frameworks (COFs) as carrier for improved drug delivery and biosensing applications

“…Given its prevalence in release studies that have been documented in prior literature, IBU was chosen as the target drug for loading and release experiments. Each COF was loaded with IBU before it was released into the phosphate buffer solution (Sellinger, 2019).…”

Construction of Thiadiazole-Bridged sp2-Carbon-Conjugated Covalent Organic Frameworks with Diminished Excitation Binding Energy Toward Superior Photocatalysis

“…Conjugated covalent organic frameworks (COFs) are porous crystalline polymers with covalent connecting repeat nodes and linkers, which are featured with well-defined pore channels, high surface area, and tunable periodic skeletons. 1−6 These merits confer COFs as promising candidates for various applications from gas storage 7 to energy conversion, 8−11 optoelectronics, 12,13 and photocatalysis. 14−17 To date, there are a series of imine, 18−20 azine, 21−24 and β-ketoenaminelinked 25−28 conjugated COFs reported.…”