Synthesis and Self‐Assembly of Bolaamphiphiles Based on β‐Amino Acids or an Alcohol

The synthesis of bolaamphiphiles from unusual β‐amino acids or an alcohol and C₁₂ or C₂₀ spacers is described. Unusual β‐amino acids such as a sugar amino acid, an AZT‐derived amino acid, a norbornene amino acid, and an AZT‐derived amino alcohol were coupled with spacers under standard conditions to get the novel bolaamphiphiles 5 – 8 (Scheme 1), 12 and 13 (Scheme 2), and 17 and 20 (Scheme 3). Some of these compounds, on precipitation from MeOH/H₂O, self‐assembled into organized molecular structures.     

Hydrophilic Carotenoids: Surface Properties and Aggregation Behavior of the Potassium Salt of the Highly Unsaturated Diacid Norbixin

The oft‐claimed ‘good’ water solubility of the food color norbixin ( 3 ) could not be confirmed. In contrast, the potassium salt 5 of norbixin formed suitable dispersions. The surface and aggregation properties of salt 5 were investigated and compared with other naturally occurring and synthetic hydrophilic carotenoids (Table).     

Synthesis and self-assembly behavior of 2,5-diphenylethynyl thiophene based bolaamphiphiles

Synthesized 2,5-diphenylethynyl thiophene based bent bolaamphiphiles can self-organize into square honeycomb LC phases with p4mm symmetries in the presence of water. UV and PL measurements indicate fl uorescent properties making them potential candidates for application in fl uorescence sensor devices     

Synthesis,chemistry, physicochemical properties and industrial applications of amino acid surfactants: A review

Surfactant use throughout mankind is extensive, from their initial applications as detergents extending to use in medicine, lubricant, cosmetics and even enhanced oil recovery. However, the image of surfactant use has in the past been tarnished by issues with low biodegradability and their synthesis from nonsustainable resources. Amino acid–based surfactants are a class of surfactants derived from a hydrophobe source coupled with simple amino acids, mixed amino acids from synthesis or from protein hydrolysates, and as such can be derived solely from renewable resources. There are several pathways for their synthesis and this allows for extensive structural diversity in this class of surfactants, resulting in widespread tuneable functionality in their physiochemical properties. This review includes the details of most of the available routes of synthesis for amino acid surfactants (AASs) and the impact of the diverse routes on their final physiochemical properties, including solubility, dispersability, toxicity and biodegradability. The diversity offered by the structural variation in AASs offers many exciting commercial opportunities for this ever-growing class of surfactants. It also includes a discussion on current and future potential uses of AASs.     

Self‐Assembly of Bolaamphiphilic Molecules

The current buzzword in science and technology is self‐assembly and molecular self‐assembly is one of the most prominent fields as far as research in chemical and biological sciences is concerned. Generally, self‐assembly of molecules occurs through weak non‐covalent interactions like hydrogen bonding, π–π stacking, hydrophobic effects, etc. Inspired by many natural systems consisting of self‐assembled structures, scientists have been trying to understand their formation and mimic such processes in the laboratory to create functional “smart” materials, which respond to temperature, light, pH, electromagnetic field, mechanical stress, and/or chemical stimuli. These responses are usually manifested as remarkable changes from the molecular (e. g., conformational state, hierarchical order) to the macroscopic level (e. g., shape, surface properties). Many molecules such as peptides, viruses, and surfactants are known to self‐assemble into different structures. Among them, glycolipids are the new entries in the area of molecules that are being investigated for their self‐assembly characteristics. Among the different classes of glycolipids like rhamnolipids and trehalose lipids, owing to their biological preparations and their structural novelty, sophorolipids (SLs) are evoking greater interest among researchers. Sophorolipids are a class of asymmetric bolas bearing COOH groups at one end and sophorose (dimeric glucose linked by an unusual β(1→2) linkage). The extreme membrane stability of Archaea, attributed to the membrane‐spanning bolas (tetraether glycolipids), has inspired chemists to unravel the molecular designs that underpin the self‐assembly of bolaamphiphilic molecules. Apart from these self‐assembled structures, bolaamphiphiles find applications in many fields such as drug delivery, membrane mimicking, siRNA therapies, etc. The first part of this Personal Account presents some possible self‐assembled structures of bolaamphiphiles and their mechanism of formation. The later part covers our work on one of the typical bolaamphiphiles known as sophorolipids.     

Self-assembly of naphthalene diimides into cylindrical microstructures

We have designed two rod-shaped compounds each incorporating a naphthalene diimide core and two terminal carboxylic acids. Both molecules aggregate in aqueous solution and spontaneously organize into cylindrical microstructures on the surface of solid substrates. Presumably, hydrogen bonds between the carboxylic acid termini and hydrophobic contacts between the naphthalene diimide cores are mainly responsible for the formation of these supramolecular arrays. Indeed, extended stacks of molecules self-assemble with close contacts between their aromatic cores in single crystals grown from polar solvents.     

Stabilization of an asymmetric bolaamphiphilic sugar-based crown ether hydrogel by hydrogen bonding interaction and its sol-gel transcription

Asymmetric bolaamphiphilic sugar-based hydrogelators (1-3) were synthesized and their gelation ability with and without alkylammonium ions was investigated by CD, TEM, FTIR and NMR. These compounds acted as versatile gelators for organic solvents and water. The xerogels 1-3 obtained from water showed well-developed structures of fibrils with diameters of 10-38 nm and length of several hundred micrometers. Particularly, the gelation ability of crown-appended gelator 1 was drastically enhanced by addition of alkylammonium ions 4 and 5, suggesting that the bridging effect of alkyldiammonium ions could be the primary driving-force for the stabilization due to the intermolecular hydrogen bonding and electrostatic interactions. The present result is a rare case of a hydrogel being stabilized by a host-guest interaction. In addition, the hydrogel 1 with AgNO₃ and KClO₄ induced the formation of nanotubular and vesicular structures of silica by sol-gel polymerization of TEOS, respectively. These results indicate that hydrogel 1 acted as a template to produce inorganic nanomaterials.