Synthesis, calorimetric studies, and crystal structures of N, O-diacylethanolamines with matched chains

Synthesis, physicochemical characterization and membrane interactions of a homologous series of N-acylserotonins: Bioactive, endogenous conjugates of serotonin with fatty acids

“…The odd-even alternation seen in the transition enthalpies, transition entropies and transition temperatures of NASTs is similar to the alternation observed previously in the thermodynamic properties of a number of other amphiphilic molecules such as long-chain hydrocarbons, fatty acids, N-acylethanolamines, N-, O-diacylethanolamines with matched as well as mixed chains, and N-acyldopamines in the solid state [26,[30][31][32][33][34]. This could be explained on the basis of differences in the packing of hydrocarbon chains.…”

“…Similarly in the hydrated state the T t ∞ values for odd and even chain-length NASTs were estimated as 395.2 and 409.8 K, respectively. For a number of diacyl lipids as well as single chain amphiphiles, which exhibit linear dependence of transition enthalpy and transition entropy on chain length, it has been shown that the data can be fit to the following equation [31,32,36]:…”

Self-assembly, supramolecular organization, and phase transitions of a homologous series of N-acyl-l-alanines (n=8–20)

“…However, when the data obtained with even-and oddchain length series are viewed together, a zig-zag pattern is seen with the values of enthalpy and entropy for the odd-chain length series being slightly higher than those of even-chain length series, i.e., the calorimetric data exhibit odd-even alteration. This observation is rather unusual since for many other homologous series such as long chain fatty acids, hydrocarbons, alcohols, N-acylethanolamines, N-acyldopamines, N-acylserotonins, and N-,O-diacylethanolamines the values of thermodynamic parameters for the odd chain length series are lower as compared to those of the even chain length series [29][30][31][32][33]. However, this type of odd-even alteration was observed earlier with phosphatidylcholines bearing -tertiary-butyl fatty acyl chains and phosphatidylcholines containing dl-methyl anteisobranched fatty acyl chains in the hydrated state [34,35].…”

Differential scanning calorimetric and powder X-ray diffraction studies on a homologous series of N-acyl-L-alanine esters with matched chains (n = 9-18)

“…19,20 The H t and S t data for odd and even acyl chain length NAAEs could be fit well to expressions (2) and (3) given below 14 as reported previously with N -acylethanolamines, N -acyldopamines, and Nacylserotonins with even and odd acyl chain lengths, O-acylcholines with even chainlengths as well as N -, O-diacylethanolamines with matched as well as mixed acyl chains. [15][16][17][18][21][22][23] When the transition enthalpies and transition entropies of NAAEs are compared with those corresponding to the single chain amphiphiles derived from L-alanine (N -acyl-L-alnines and L-alanine alkyl esters), 6,7 it is seen that NAAEs exhibit higher values of H t and S t for the solid to liquid transition, which could be attributed to the high molecular weight of the NAAEs. On the other hand, when compared to the N , O-diacylethanolamines (DAEs, which differ from the NAAEs only in the head group region, due to the presence of the α-methyl group and the reversal of the connectivity between the ester carbonyl and oxygen) the corresponding values are lower, which could be due to the bulkier head group (due to methyl substitution), which could prevent tight packing of the NAAE molecules in the crystal lattice.…”

“…16 In the supramolecular organization of DAE molecules in the crystal, the N -acyl and O-acyl chains face each other. 16 The present PXRD data on NAAEs would be consistent with both these packing arrangements and further studies are required to distinguish between them.…”