Leveraging Torsional and Steric Strains: A Pre-macrocyclization Strategy Enables Conformation-Specific Fullerene Binding in m-Cyclophanes

Though the chemistry of resorcinarenes is half a century old, the conformationally-locked resorcinarene crowns are generally constructed using hydrogen bonds or covalent tethers. Often, covalent tethering involves extra post-macrocyclization steps involving upper-rim functionalities. We have leveraged the torsional and steric strains through α-substituents of the lower-rim C-alkyl chains and accomplished conformationally-rigid fluorescent m-cyclophane deep-crowns in a predetermined way. The strategy offers a pre-macrocyclization route conserving upper-rim functionalities, an aspect overlooked in resorcinarene chemistry. X-ray structural and computational analyses unveil the cause for conformational rigidity in m-cyclophanes due to α-branching in C-alkyls (linear vs. α-/β-branched). The conformationally-locked fluorescent deep-crown with a preorganized cavity captures hydrophobic spherical guest C60 in both solution and solid states specifically, when compared to conformationally-dynamic boats, enabling conformation-specific binding.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2013-2014

This review is the eighth update of the original article published in 1999 on the application of Matrix-assisted laser desorption/ionization mass spectrometry (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2014. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation, and arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly- saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2018 Wiley Periodicals, Inc. Mass Spec Rev 37:353-491, 2018.

Green Processing of Carbon Nanomaterials

Carbon nanomaterials (CNMs) from fullerenes, carbon nanotubes, and graphene are promising carbon allotropes for various applications such as energy-conversion devices and biosensors. Because pristine CNMs show substantial van der Waals interactions and a hydrophobic nature, precipitation is observed immediately in most organic solvents and water. This inevitable aggregation leads to poor processability and diminishes the intrinsic properties of the CNMs. Highly toxic and hazardous chemicals are used for chemical and physical modification of CNMs, even though efficient dispersed solutions are obtained. The development of an environmentally friendly dispersion method for both safe and practical processing is a great challenge. Recent green processing approaches for the manipulation of CNMs using chemical and physical modification are highlighted. A summary of the current research progress on: i) energy-efficient and less-toxic chemical modification of CNMs using covalent-bonding functionality and ii) non-covalent-bonding methodologies through physical modification using green solvents and dispersants, and chemical-free mechanical stimuli is provided. Based on these experimental studies, recent advances and challenges for the potential application of green-processable energy-conversion and biological devices are provided. Finally, a conclusion section is provided summarizing the insights from the present studies as well as some future perspectives.

A peptide topological template for the dispersion of [60]fullerene in water

Stable dispersions of [60]fullerene in water with concentrations of up to 1.3 mg mL⁻¹ have been obtained using a peptide topological template as the carrier.