Formation of molecular glasses and the aggregation in solutions for lanthanum(iii), calcium(ii), and yttrium(iii) complexes of octanoyl-dl-alaninate

Abstract

Octanoylalaninato-metal (metal = calcium(II), yttrium(III), lanthanum(III), and zinc(II)) complexes were prepared and the first three metal complexes were found to readily form transparent and stable molecular glasses from methanol and chloroform solutions. The process of glass formation from solution was studied in detail. The effect of the central metal ions on the formation of glassy states was remarkable: the lanthanum and calcium complexes assumed glassy or crystalline states depending on the isolation method and the yttrium complex had a large tendency to assume an amorphous state, whereas the zinc complex did not assume a pure and stable glassy-state. The glass transition temperatures were 50 degrees C for the yttrium complex and 70-75 degrees C for the lanthanum and calcium complexes when these complexes are monohydrates prepared by a solvent-cast method, whereas they increase by 10-30 degrees for the hemihydrates which were obtained by an annealing treatment at 110 degrees C. The coordinated water was eliminated from the solid above the glass transition temperature. The glassy state was regarded as a result of the self-aggregation of the metal complex in solution by an entanglement of the methylene chains with one another. SAXS showed the presence of two disordered bilayer structures with 2.2 nm and 4.5 nm periods in the glassy states. The structures of the molecular assemblies in the solid states and solutions were compared by SAXS and NMR studies. EXAFS studies confirmed the coordination numbers of oxygen atoms around the yttrium and lanthanum atoms in the glassy states for the yttrium and lanthanum complexes to be about 7.

Properties of ionic liquids containing silver(I) or protic alkylethylenediamine cations with a bis(trifluoromethanesulfonyl)amide anion

“…The remarkable difference in the properties between the hexyl and 2-ethylhexyl complexes was clarified for complexes with PF À 6 and NO À 3 counter anions, respectively. That study has been performed as one of those on metallosurfactants which sometimes showed unique aggregation states such as molecular glasses and liquid crystalline glasses [32,33].…”

Synthesis, Characterization, and DFT studies of Praseodymium (III) Octanoyl‐DL‐aminocarboxylate Complexes

“…2 θ =20° for all praseodymium(III) complexes indicates in‐plane disorder (i. e. disorder in alkyl‐chains). It originates from the disordered methylene‐methylene interaction [6] . This amorphous peak highlights the glassy state of the praseodymium(III) complexes.…”

“…The organo‐lanthanide complexes, in particular, have attracted organic chemists. In recent years, the octanoyl‐aminocarboxylates complexes of lanthanum(III), [6] magnesium(II), calcium(II), [7] yttrium(III), [8] europium(III), [9] and terbium(III) [10] have been synthesized, and their optical performance was verified through experiments. Usually, studies of optical properties of rare earth metal complexes focus on europium and terbium ions, and little on the praseodymium(III) complex.…”

Synthesis and Optical Absorption Properties of Yttrium (III) Acylaminocarboxylates Complexes

“…SAXS profiles are usually expected to provide information on supramolecular structures in solid state [8]. Fig.…”