New pyridinium gemini surfactants have been synthesized by esterification of halogenated carboxylic acids with long chain fatty alcohols furnishing respective esters (dodecyl‐2‐chloroacetate, tetradecyl‐2‐chloroacetate, hexadecyl‐2‐chloroacetate, dodecyl‐2‐bromoacetate, tetradecyl‐2‐bromoacetate and hexadecyl‐2‐bromoacetate) followed by their subsequent treatment with 4,4′‐trimethylene dipyridine resulting in the formation of title Gemini surfactants: 4,4′‐(propane‐1,3‐diyl)bis1‐{2‐(dodecyloxy)‐2‐oxoethyl}; 4,4′‐(propane‐1,3‐diyl)bis{1‐(2‐(tetradecyloxy)‐2‐oxoethyl}; 4,4′‐(propane‐1,3‐diyl)bis{1‐(2‐(hexadecyloxy)‐2‐oxoethyl} dipyridinium chlorides; 4,4′‐(propane‐1,3‐diyl)bis{1‐(2‐(dodecyloxy)‐2‐oxoethyl}; 4,4′‐(propane‐1,3‐diyl)bis{1‐(2‐(tetradecyloxy)‐2‐oxoethyl} and 4,4′‐(propane‐1,3‐diyl)bis{1‐(2‐(hexadecyloxy)‐2‐oxoethyl} dipyridinium bromides. Their identifications are based on IR, 1H‐NMR, 13C‐NMR, DEPT, COSY and Mass spectral studies. Their surface active properties were also evaluated on the basis of surface tension and conductivity measurements.

New imidazolium gemini surfactants were synthesized by reaction of epichlorohydrin with long chain fatty alcohols furnishing products 2‐(alkoxymethyl)oxirane followed by their subsequent treatment with imidazole resulting in the formation of 1‐(1H‐imidazol‐1‐yl‐3 alkoxy)propane‐2‐ol which on subsequent treatment with 1,2‐dibromoethane and 1,3‐dibromopropane resulted in the formation of title gemini surfactants:1,2‐bis(1(3‐alkoxy‐2‐hydroxypropyl)‐1H‐imidazol‐3‐ium)ethane bromide (7), 1,3‐bis(1(3‐alkoxy‐2‐hydroxypropyl)‐1H‐imidazol‐3‐ium)propane bromide (8), 1,2‐bis(1(3‐alkoxy‐2‐hydroxypropyl)‐1H‐imidazol‐3‐ium)ethane bromide (9), 1,3‐bis(1(3‐alkoxy‐2‐hydroxypropyl)‐1H‐imidazol‐3‐ium)propane bromide (10), 1,2‐bis (1(3‐alkoxy‐2‐hydroxypropyl)‐1H‐imidazol‐3‐ium)ethane bromide (11) and 1,3‐bis (1(3‐alkoxy‐2‐hydroxypropyl)‐1H‐imidazol‐3‐ium)propane bromide (12). Their identification was based on IR, 1H‐, 13C‐NMR, DEPT, COSY and mass spectral studies. Their surface active properties were also evaluated on the basis of surface tension and conductivity measurements.

New pyridinium Gemini surfactants have been synthesized by esterification of renewable fatty acids with halogenated alcohols furnishing respective esters (2‐chloroethyl hexadecanoate, 2‐chloroethyl tetradecanoate, 2‐chloroethyl dodecanoate, 2‐bromoethyl hexadecanoate, 2‐bromoethyl tetradecanoate and 2‐bromoethyl dodecanoate) followed by their subsequent treatment with 4,4′‐trimethylenedipyridine resulting into the formation of title Gemini surfactants: (4,4′‐(propane‐1,3‐diyl)bis(1‐(2‐(hexadecanoyl oxy) ethyl) dipyridinium chloride(7), (4,4′‐(propane‐1,3‐diyl)bis(1‐(2‐(tetradecanoyl oxy) ethyl) dipyridinium chloride (8), 4,4′‐(propane‐1,3‐diyl)bis(1‐(2‐(dodecanoyl oxy) ethyl) dipyridinium chloride (9), (4,4′‐(propane‐1,3‐diyl)bis(1‐(2‐(hexadecanoyl oxy) ethyl) dipyridinium bromide (10), (4,4′‐(propane‐1,3‐diyl)bis(1‐(2‐(tetradecanoyl oxy) ethyl) dipyridinium bromide (11), 4,4′‐(propane‐1,3‐diyl)bis(1‐(2‐(dodecanoyl oxy) ethyl) dipyridinium bromide (12). Their identifications are based on IR, 1H‐, 13C‐NMR, DEPT, COSY and mass spectral studies. Their surface active properties are also evaluated on the basis of surface tension and conductivity measurements and thermal stability of these long chain cationics Gemini surfactants have been measured by thermal gravimetric analysis under nitrogen atmosphere.

A series of long‐chain ester‐based water‐soluble cationics have been synthesized by using renewable raw materials like fatty acids and halogenated alcohols. The surface activity of the molecules has been determined by measurement of their conductance and surface tension in aqueous solution. The dynamics of surface activity of these surfactants have also been investigated in the presence of sodium halides (NaCl and NaBr) by surface tension measurement. A series of useful parameters like critical micelle concentration (CMC), surface tension at the CMC (γCMC), adsorption efficiency (pC20), effectiveness of surface tension reduction (ΠCMC), Gibbs free energy of the micellization (ΔG0mic) and Gibbs free energy of adsorption (ΔG0ads) have been determined from the measurements obtained by surface tension and conductivity methods. Further with the application of the Gibbs adsorption isotherm, maximum surface excess concentration (Γmax) and minimum surface area/molecule (Amin) at the air–water interface were also estimated. Thermal stability of these long chain cationics have been measured by thermal gravimetric analysis under a nitrogen atmosphere. Analysis of thermal stability measurement indicated that the thermal stability of these long chain imidazoliums increases with an increase in chain length.

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