Shedding Light on the Protonation States and Location of Protonated N Atoms of Adenine in Metal-Organic Frameworks

Structural Effect of N-7 Alkylation in 6-Chloropurine on Cu (II) Binding: Effect of Anions and Magnetic Studies

This study investigates the anion-directed assembly of discrete copper (II) complexes. The ligands of choice are two N7-alkyl-purine-based neutral ligands. These ligands facilitate the exclusive coordination through the N3 and N9 positions, preventing polymeric chain formation. Perchlorate ions promoted the formation of discrete paddlewheel-like complexes with the general formula [Cu2(μ-Pur)4(CH3CN)2]4+, while chloride ions yielded chloride-bridged dimers of the form [Cu2(Pur)2(μ-Cl)2Cl2]. Copper-copper bond distances within these complexes ranged from 2.92 to 2.98 Å. Magnetic susceptibility measurement of chloride-bridged complexes exhibited antiferromagnetic coupling, whereas paddlewheel complexes displayed more complex alternating ferromagnetic and antiferromagnetic interactions. Chloride-bridged compounds exhibited strong near-infrared absorption.

Electrochemical energy storage in an organic supercapacitor via a non-electrochemical proton charge assembly

Contrary to conventional beliefs, we show how a functional ligand that does not exhibit any redox activity elevates the charge storage capability of an electric double layer via a proton charge assembly. Compared to an unsubstituted ligand, a non-redox active carboxy ligand demonstrated nearly a 4-fold increase in charge storage, impressive capacitive retention even at a rate of 900C, and approximately a 2-fold decrease in leakage currents with an enhancement in energy density up to approximately 70% via a non-electrochemical route of proton charge assembly. Generalizability of these findings is presented with various non-redox active functional units that can undergo proton charge assembly in the ligand. This demonstration of non-redox active functional units enriching supercapacitive charge storage via proton charge assembly contributes to the rational design of ligands for energy storage applications.

Click-derived multifunctional metal complexes for diverse applications

The Click reaction that involves Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) serves as the most potent and highly dependable tool for the development of many complex architectures. It has paved the way for the synthesis of numerous drug molecules with enhanced synthetic flexibility, reliability, specificity and modularity. It is all about bringing two different molecular entities together to achieve the required molecular properties. The utilization of Click chemistry has been well demonstrated in organic synthesis, particularly in reactions that involve biocompatible precursors. In pharmaceutical research, Click chemistry is extensively utilized for drug delivery applications. The exhibited bio-compatibility and dormancy towards other biological components under cellular environments makes Click chemistry an identified boon in bio-medical research. In this review, various click-derived transition metal complexes are discussed in terms of their applications and uniqueness. The scope of this chemistry towards other streams of applied sciences is also discussed.

Recent Advancements in MOF/Biomass and Bio-MOF Multifunctional Materials: A Review

Metal–organic frameworks (MOFs) and their derivatives have delivered perfect answers in detection, separation, solving water and electromagnetic pollution and improving catalysis and energy storage efficiency due to their advantages including their highly tunable porosity, structure and versatility. Recently, MOF/biomass, bio-MOFs and their derivatives have gradually become a shining star in the MOF family due to the improvement in the application performance of MOFs using biomass and biomolecules. However, current studies lack a systematic summary of the synthesis and advancements of MOF/biomass, bio-MOFs and their derivatives. In this review, we describe their research progress in detail from the following two aspects: (1) synthesis of MOF/biomass using biomass as a template to achieve good dispersion and connectivity at the same time; (2) preparing bio-MOFs by replacing traditional organic linkers with biomolecules to enhance the connection stability between metal ions/clusters and ligands and avoid the formation of toxic by-products. This enables MOFs to possess additional unique advantages, such as improved biocompatibility and mechanical strength, ideal reusability and stability and lower production costs. Most importantly, this is a further step towards green and sustainable development. Additionally, we showcase some typical application examples to show their great potential, including in the fields of environmental remediation, energy storage and electromagnetic wave absorption.

Copper–carbon dot aerogel: a high-performance mimetic peroxidase and its application for versatile colorimetric bioassays

Benefiting from the electron transfer process and generation of hydroxyl radical, copper–carbon dot aerogels exhibit high-performance peroxidase-like activity and are applied for versatile colorimetric bioassays based on multienzyme cascade reactions.

Towards a Molecular Understanding of Cation-Anion Interactions and Self-aggregation of Adeninate Salts in DMSO by NMR and UV Spectroscopy and Crystallography

Rare anionic forms of nucleic acids play a significant biological role and lead to spontaneous mutations and replication and translational errors. There is a lack of information surrounding the stability and reactivity of these forms. Ion pairs of mono‐sodium and ‐potassium salts of adenine exist in DMSO solution with possible cation coordination sites at the N1, N7 and N9 atoms of the purine ring. At increasing concentrations π‐π stacked dimers are the predominant species of aggregates followed by higher order aggregation governed by coordination to metal cations in which the type of counter ion present has a central role in the aggregate formation.

One-Pot Preparation of Peptide-Doped Metal-Amino Acid Framework for General Encapsulation and Targeted Delivery

Metal-organic frameworks (MOFs), especially those made by biological molecules (bio-MOFs), have been proved to be prospective candidates for biomedical applications. However, a simple and universal bio-MOF to load different substances for precise targeting is still lacking. In this work, we propose a facile one-pot method to prepare a peptide-doped bio-MOF for general encapsulation and targeted delivery. This bio-MOF is constructed by 9-fluorenylmethyloxycarbonyl-modified histidine (Fmoc-His) as a bridging linker that coordinates with Zn2+ ions, denoted as ZFH. The Fmoc-His-Asp-Gly-Arg peptide (Fmoc-HDGR) can be easily doped into the ZFH structure with different ratios to modulate the targeting ability of ZFH-DGR. Containing both hydrophobic Fmoc and hydrophilic His moieties, this framework is compatible with encapsulating various types of payloads, including hydrophobic chemotherapeutic, hydrophilic protein, and positively/negatively charged inorganic nanoparticles. It has also been proved to be highly biocompatible and stable in circulation, exhibit the capabilities to target ανβ3 integrin overexpressed on tumor cells, and trigger drug release in a low pH microenvironment at the tumor site. As a proof of concept, Doxorubicin (Dox)-loaded ZFH-DGR (ZFH-DGR/Dox) demonstrated high cell selectivity between liver hepatocellular carcinoma (HepG2) cells and normal liver (L02) cells, which express high and low ανβ3 integrin, respectively. This selectivity endows ZFH-DGR/Dox precise treatment and low toxicity in Heps-bearing liver cancer mice. This work develops a de novo approach to construct a peptide-doped bio-MOF system for universal load, precise delivery, and peptide drug combination therapy in the future.

Nucleobase pairing and photodimerization in a biologically derived metal-organic framework nanoreactor

Biologically derived metal-organic frameworks (bio-MOFs) are of great importance as they can be used as models for bio-mimicking and in catalysis, allowing us to gain insights into how large biological molecules function. Through rational design, here we report the synthesis of a novel bio-MOF featuring unobstructed Watson-Crick faces of adenine (Ade) pointing towards the MOF cavities. We show, through a combined experimental and computational approach, that thymine (Thy) molecules diffuse through the pores of the MOF and become base-paired with Ade. The Ade-Thy pair binding at 40–45% loading reveals that Thy molecules are packed within the channels in a way that fulfill both the Woodward-Hoffmann and Schmidt rules, and upon UV irradiation, Thy molecules dimerize into Thy<>Thy. This study highlights the utility of accessible functional groups within the pores of MOFs, and their ability to ‘lock’ molecules in specific positions that can be subsequently dimerized upon light irradiation, extending the use of MOFs as nanoreactors for the synthesis of molecules that are otherwise challenging to isolate.

Metal-organic frameworks have shown promise as nanoreactors, facilitating the synthesis of molecules that are otherwise difficult to isolate. Here, the authors design a framework featuring unobstructed adenine linkers to which thymine molecules can base-pair, allowing for thymine dimerization in the pores upon UV irradiation.