Lanthanide Phytanates: Liquid-Crystalline Phase Behavior, Colloidal Particle Dispersions, and Potential as Medical Imaging Agents

Abstract

Lanthanide salts of phytanic acid, an isoprenoid-type amphiphile, have been synthesized and characterized. Elemental analysis and FTIR spectroscopy were used to confirm the formed product and showed that three phytanate anions are complexed with one lanthanide cation. The physicochemical properties of the lanthanide phytanates were investigated using DSC, XRD, SAXS, and cross-polarized optical microscopy. Several of the hydrated salts form a liquid-crystalline hexagonal columnar mesophase at room temperature, and samarium(III) phytanate forms this phase even in the absence of water. Select lanthanide phytanates were dispersed in water, and cryo-TEM images indicate that some structure has been retained in the dispersed phase. NMR relaxivity measurements were conducted on these systems. It has been shown that a particulate dispersion of gadolinium(III) phytanate displays proton relaxivity values comparable to those of a commercial contrast agent for magnetic resonance imaging and a colloidal dispersion of europium(III) phytanate exhibits the characteristics of a fluorescence imaging agent.

Enhanced energy transfer efficiency and stability of europium β-diketonate complex in ionic liquid-based lyotropic liquid crystals

“…19 Parac-Vogt et al reported the effectively decreased luminescence quenching of dysprosium complexes and thus, increased quantum yields in the micellar aqueous solution of Tween 80. 21 In aqueous hexagonal and lamellar lyotopic liquid crystals (LLCs) fabricated from europium phytanate 22 and oleate 23 complexes, the protection effect of europium ions with respect to water molecules was observed by Drummond et al We have also recently reported the enhanced luminescent properties of europium ions dispersed in LLCs, constructed from their hydrate salt and triblock amphiphilic copolymers. 21 In aqueous hexagonal and lamellar lyotopic liquid crystals (LLCs) fabricated from europium phytanate 22 and oleate 23 complexes, the protection effect of europium ions with respect to water molecules was observed by Drummond et al We have also recently reported the enhanced luminescent properties of europium ions dispersed in LLCs, constructed from their hydrate salt and triblock amphiphilic copolymers.…”

“…[19][20][21][22][23] For example, a significant luminescence enhancement can be obtained in electrostatic micelles, formed between the negatively charged coordination compound Eu-L 2 EO 4 (1,11-bis(2,6-dicarboxypyridin-4-yloxy)-3,6,9-trioxaundecane) and positively charged block polyelectrolytes. [19][20][21][22][23] For example, a significant luminescence enhancement can be obtained in electrostatic micelles, formed between the negatively charged coordination compound Eu-L 2 EO 4 (1,11-bis(2,6-dicarboxypyridin-4-yloxy)-3,6,9-trioxaundecane) and positively charged block polyelectrolytes.…”

Rational chemical design of the next generation of molecular imaging probes based on physics and biology: mixing modalities, colors and signals

“…130 Lanthanide doped nanocrystals are potentially important as bimodal nanoprobes because they are capable of exciting fluorophores deep in the body yet, demonstrate excellent photostability, and minimal autofluorescence. 132,134–138,141,142 …”

The search for new amphiphiles: synthesis of a modular, high-throughput library

“…These consisted of saturated chains with systematic ethylene increases between (CH 2 ) 6 CH 3 (abbreviated to C7) and (CH 2 ) 16 CH 3 , as well as branched (phytanic), monounsaturated (palmitoleic, oleic and erucic) and polyunsaturated (linoleic) chains, which have been shown to promote the formation of inverse hexagonal and/or inverse bicontinuous cubic lyotropic phases in related systems [36–38]. …”