Structural and Solubility Parameter Correlations of Gelation Abilities for Dihydroxylated Derivatives of Long‐Chain, Naturally Occurring Fatty Acids

Abstract

Creating structure-property correlations at different distance scales is one of the important challenges to the rational design of molecular gelators. Here, a series of dihydroxylated derivatives of long-chain fatty acids, derived from three naturally occurring molecules-oleic, erucic and ricinoleic acids-are investigated as gelators of a wide variety of liquids. Conclusions about what constitutes a more (or less!) efficient gelator are based upon analyses of a variety of thermal, structural, molecular modeling, and rheological results. Correlations between the manner of molecular packing in the neat solid or gel states of the gelators and Hansen solubility data from the liquids leads to the conclusion that diol stereochemistry, the number of carbon atoms separating the two hydroxyl groups, and the length of the alkanoic chains are the most important structural parameters controlling efficiency of gel formation for these gelators. Some of the diol gelators are as efficient or even more efficient than the well-known, excellent gelator, (R)-12-hydroxystearic acid; others are much worse. The ability to form extensive intermolecular H-bonding networks along the alkyl chains appears to play a key role in promoting fiber growth and, thus, gelation. In toto, the results demonstrate how the efficiency of gelation can be modulated by very small structural changes and also suggest how other structural modifications may be exploited to create efficient gelators.

Insights into the Gelating Abilities of Ricinelaidic Acid and its Ammonium Salts: How do Stereochemistry, Charge, and Chain Lengths Control Gelation of a Long‐Chain Alkenoic Acid?

“…PXRD diffractograms of the neat ammonium ricinelaidates and their 5 wt % fast‐cooled gels in nitrobenzene were also obtained (Figure and Figure S6). When a sufficient number of diffraction peaks were available, cell constants and Bragg spacings ( d ) of the neat gelators were calculated (Table ) …”

“…In this regard, we have investigated the gelating abilities of a number of long‐chain, naturally‐occurring fatty acids in which minor additions and deletions of functional groups have been introduced . Among them are derivatives and isomers of the well‐known and very efficient fatty acid gelator, ( R )‐12‐hydroxystearic acid ( d ‐12HSA) . Here, we investigate the gelating abilities of ricinelaidic acid ( d ‐REA) and its salts (made with n ‐alkylamines or alkane‐α,ω‐diamines) (Scheme ) and the properties of their gels in a wide range of organic liquids.…”

Mechano‐Responsive, Thermo‐Reversible, Luminescent Organogels Derived from a Long‐Chained, Naturally Occurring Fatty Acid

“…[7,10] Naturally occurring fatty acids and their derivatives are available as triglycerides in many plant-seed oils. [13] They have garnered considerable interest recentlya sm olecular gelators [14] becausem any structural modifications are possible, and those changes can be correlated with gelator efficiency.F or example, stearic acid (SA), which contains only one H-bond donation and acceptance site, is av ery inefficient gelator (Scheme 1). [15] Whereas 10-oxooctadecanoic acid (10-KSA), am onoketo derivative,i sarelatively efficient gelatora saresult of its added abilityt oi nitiate intermolecular keto-keto dipolar interactions along the polymethylene chain.…”

Organogel Formation Rationalized by Hansen Solubility Parameters: Shift of the Gelation Sphere with the Gelator Structure

“…4 The next challenge in the field is to evaluate how small changes in the structure of a LMWG will affect the gelation domain. [27][28][29][30][31][32][33] In particular, we previously probed the influence of the length of an alkyl chain within a family of related gelators, but showed that it is difficult to rationalize the results without knowledge of the molecular packing. 33 To better correlate the molecular structure with the gelation domain, we selected a family of amide-based thiazole derivatives bearing a long aliphatic chain, for which the elucidation of the molecular packing seemed to be within reach ( Figure 1).…”