We have collated various supramolecular designs that utilize organic donor–acceptor CT complexation to generate noncovalently co‐assembled structures including fibrillar gels, micelles, vesicles, ...nanotubes, foldamers, conformationally restricted macromolecules, and liquid crystalline phases. Possibly inspired by nature, chemists have extensively used hydrogen bonding as a tool for supramolecular assemblies of a diverse range of abiotic building blocks. As a structural motif, CT complexes can be compared to hydrogen‐bonded complexes in its directional nature and complementarities. Additional advantages of CT interactions include wider solvent tolerance and easy spectroscopic probing. Nevertheless the major limitation is their low association constant. This article shows different strategies have evolved over the years to overcome this drawback by reinforcing the CT interactions with auxiliary noncovalent forces without hampering the alternate stacking mode. Emerging reports on promising CT complexes in organic electronics are intimately related to various supramolecular designs that one can postulate based on donor–acceptor CT interactions.
Riot of color: Alternate stacking of aromatic donor and acceptor building blocks by complementary and directional charge‐transfer interactions produce versatile supramolecularly assembled materials including micelles, vesicles, nanotubes, fibrillar gels, folded polymers, cross‐linked networks, and liquid‐crystalline phases.
The outbreak of coronavirus disease 2019 (COVID-19), an infectious disease with severe acute respiratory syndrome, has now become a worldwide pandemic. Despite the respiratory complication, COVID-19 ...is also associated with significant multiple organ dysfunction, including severe cardiac impairment. Emerging evidence reveals a direct interplay between COVID-19 and dire cardiovascular complications, including myocardial injury, heart failure, heart attack, myocarditis, arrhythmias as well as blood clots, which are accompanied with elevated risk and adverse outcome among infected patients, even sudden death. The proposed pathophysiological mechanisms of myocardial impairment include invasion of SARS-CoV-2 virus via angiotensin-converting enzyme 2 to cardiovascular cells/tissue, which leads to endothelial inflammation and dysfunction, de-stabilization of vulnerable atherosclerotic plaques, stent thrombosis, cardiac stress due to diminish oxygen supply and cardiac muscle damage, and myocardial infarction. Several promising therapeutics are under investigation to the overall prognosis of COVID-19 patients with high risk of cardiovascular impairment, nevertheless to date, none have shown proven clinical efficacy. In this comprehensive review, we aimed to highlight the current integrated therapeutic approaches for COVID-19 and we summarized the potential therapeutic options, currently under clinical trials, with their mechanisms of action and associated adverse cardiac events in highly infectious COVID-19 patients.
Controlling nanoparticles with atomic precision has long been a major dream of nanochemists. This dream has first been realized in the case of gold nanoparticles. We previously discussed a ...size-focusing methodology for the syntheses of atomically precise gold nanoclusters protected by thiolate ligands (referred to as Au n (SR) m , where n and m represent the exact numbers of gold atoms and surface ligands). This methodology led to molecularly pure nanoclusters such as Au25(SR)18, Au38(SR)24, Au144(SR)60, and many others in recent work. In this Perspective article, we shall further discuss a new methodology for controlling the size and structure of nanoclusters through ligand-exchange-induced transformation of Au n (SR) m nanoclusters. Notable examples include the transformations of Au25(SR)18 to Au28(SR′)20, Au38(SR)24 to Au36(SR′)24, and Au144(SR)60 to Au133(SR′)52. Total structures of the new nanoclusters have also been attained. The transformation processes are remarkable and resemble the organic transformation chemistry. We have also achieved mechanistic understanding on the transformation process, and a disproportionation mechanism has been for the first time identified. This new methodology (i.e., ligand-exchange-induced size/structure transformation, LEIST for short) has not only demonstrated the important role of thiolate ligand in the transformation chemistry of clusters but also paved the way for creating an expanded “library” of Au n (SR) m nanoclusters for exploration of their magic sizes, structures, properties, and applications.
Synthesis of functional polyacrylates by 4-dimethylaminopyridine (DMAP) catalyzed trans-esterification of poly(pentafluorophenyl acrylate) (polyPFPA) is reported. High fidelity and versatility of ...this strategy was exemplified by near quantitative conversion with diverse functional alcohols (primary, secondary as well as phenolic) featuring reactive groups like alkene, alkyne or acrylate, enabling further sequential functionalization using click chemistry. Co-integrating an equimolar mixture of allyl and propargyl alcohol produced an orthogonally clickable copolymer by thiol–ene and 1,3-cycloaddition reaction. Base catalyzed ester exchange allowed installation of acid labile Boc-l-serine to create amino acid pendent polymer keeping both NH2- and COOH-group free, thereby providing a facile route toward zwitterionic polymers. Reaction with 2-dimethylaminoethanol conferred dual pH and CO2 responsive polymers from the same reactive precursor. The synthetic strategy was further extended to attach alcohols obtained from natural resources such as geraniol, l-lactic acid or sesamol to engineer new renewable polymers. Even a graft copolymer with very high (93%) grafting density could be achieved utilizing PEG350–OH. The trans-esterification was found to be highly selective for primary alcohols over secondary alcohols and also to the activated PFP-ester over a normal ester such as poly(methyl acrylate). Using such selectivity, fluorescently tagged polymer could be synthesized by replacing only the PFP-ester of a poly(methyl acrylate-co-PFPA) with 1-pyrenemethanol. Further, PFPA was polymerized with 2.0 mol % diacrylate to produce a cross-linked gel network. The PFP-ester groups of the cross-linked gel could be quantitatively replaced with Boc- l-serine, which upon deprotection of the Boc group resulted in a novel zwitterionic hydrogel exhibiting pH-dependent swelling properties. Time-dependent FTIR experiment suggested fast kinetics of the reaction, making this synthetic route practically applicable for postpolymerization modification. Mechanistic investigation exposed involvement of both DMAP and the nucleophilic solvent N,N-dimethylformamide (DMF) in catalyzing the reaction. This also explains the reason as to why near quantitative conversion was achieved in DMF and not in the non-nucleophilic solvent 1,4-dioxane.
We report the crystal structure of a new nanocluster formulated as Au28(TBBT)20, where TBBT = 4-tert-butylbenzenethiolate. It exhibits a rod-like Au20 kernel consisting of two interpenetrating ...cuboctahedra. The kernel is protected by four dimeric “staples” (-SR-Au-SR-Au-SR-) and eight bridging thiolates (-SR-). The unit cell of Au28(TBBT)20 single crystals contains a pair of enantiomers. The origin of chirality is primarily rooted in the rotating arrangement of the four dimeric staples as well as the arrangement of the bridging thiolates (quasi-D 2 symmetry). The enantiomers were separated by chiral HPLC and characterized by circular dichroism spectroscopy.
The mechanistic/mammalian target of rapamycin (mTOR), a member of the phosphoinositide 3-kinase (PI3K) related kinase family, integrates intracellular and environmental cues that coordinate a diverse ...set of cellular/tissue functions, such as cell growth, proliferation, metabolism, autophagy, apoptosis, longevity, protein/lipid/nucleotide synthesis, and tissue regeneration and repair ...
A versatile method for the design of colloidal crystals involves the use of DNA as a particle-directing ligand. With such systems, DNA-nanoparticle conjugates are considered programmable atom ...equivalents (PAEs), and design rules have been devised to engineer crystallization outcomes. This work shows that when reduced in size and DNA grafting density, PAEs behave as electron equivalents (EEs), roaming through and stabilizing the lattices defined by larger PAEs, as electrons do in metals in the classical picture. This discovery defines a new property of colloidal crystals-metallicity-that is characterized by the extent of EE delocalization and diffusion. As the number of strands increases or the temperature decreases, the EEs localize, which is structurally reminiscent of a metal-insulator transition. Colloidal crystal metallicity, therefore, provides new routes to metallic, intermetallic, and compound phases.
PDF
