Using reversible non-covalent and covalent bonds to create assemblies and equilibrating molecular networks that survive 5 molar urea

Abstract

Molecules that assemble through reversible covalent and noncovalent interactions achieve self-assembly at extreme levels of urea and NaCl.

Parallel Synthesis and Screening of Supramolecular Chemosensors that Achieve Fluorescent Turn-On Detection of Drugs in Saliva

“…Many classes of drugs, including opioids, amphetamines, tropane alkaloids, and anaesthetics, contain a hydrophobic cation in their structure that we hypothesized would be recognized by sulfonatocalix [4]arenebased hosts. Since DD1 15 and other related molecules 27,[36][37] can assemble and/or bind guests in competitive aqueous buffers, we envisioned that this property could be extended to sensing drugs in biofluids. Unlike most supramolecular host-guest projects, we eschewed the atomic design of sensors that would be highly specific for individual drug molecules.…”

Mechanism of a Disassembly Driven Sensing System Studied by Stopped-Flow Kinetics

“…31-32 At pH 6.3 (one anionic phenol, Scheme 1) and at pH 12.1 (>1 anionic phenol) DD1 exists as the non-fluorescent dimeric DD12 (inset Figure 1a,b). 26 At pH 2.2, some fluorescence is observed (Figure 1b), indicating the presence of the fluorescent monomer DD1. This weakening of the dimer is likely due to the pH being lower than the pKa of the hydroxyl group on the lower rim of DD1.…”

“…25 Analogs that include an integrated fluorescent component are called DimerDyes. [26][27] The self-assembly of DimerDyes stacks two dye copies in an antiparallel, quenching arrangement. The addition of a good guest out-competes homodimerization to form a host-guest complex, resulting in a turn-on fluorescence response (Scheme 1).…”

“…The association and dissociation processes cannot be determined separately and the fastest unimolecular reaction determines the time scale for the kinetics measurements. 35 The broadening observed in the 1 H NMR spectra for DimerDye-guest systems, [26][27] suggests that the dynamics for these systems occur on the millisecond time-scale, making stopped-flow the suitable technique for real-time kinetic measurements. 35 The kinetics for DD12 disassembly upon dilution was measured by the appearance of fluorescence from monomeric DD1 (Figure 2b).…”

Mechanism of a Disassembly-Driven Sensing System Studied by Stopped-Flow Kinetics

“…The addition of a good guest out-competes homodimerization to form a host−guest complex, resulting in a turn-on fluorescence response (Scheme 1). These disassembly driven systems are inherently resistant to interference from competing cosolutes, 28 making them well suited to many biosensing tasks. As discrete assemblies, DimerDyes are uniquely well suited to detailed mechanistic characterization.…”