T
he information about molecular interactions in aqueous and CCl
4 solutions involving 18-crown-6 (18C6)
have been obtained by applying Kirkwood&ndas
h;Buff t
heory at 298.15 K. T
he Kirkwood&ndas
h;Buff (KB) integrals
Gij, defined by equation
Gij=∫0∞(gij−1)4πr2dr,
have been evaluated using t
he experimental osmotic coefficient (and
hence activity coefficient) and partial molar volume data. T
he concentration range used for 18C6 is 0.001&ndas
h;0.035
x2 for aqueous solutions w
hile it is 0.01&ndas
h;0.14
x2 for CCl
4 solutions (
x2 being t
he mole fraction of 18C6). T
he limiting values of KB integrals,
Gij0, are compared wit
h molecular interaction parameters (solute&ndas
h;solute i.e. osmotic second virial coefficient) obtained recently for t
hese solutions using McMillan&ndas
h;Mayer t
heory of solutions. T
he agreement between two approac
hes is found to be satisfactory. T
he results of
Gij are interpreted in terms of
hydrop
hobic
hydration in dilute concentration range and
hydrop
hobic interaction between 18C6 molecules at
hig
her concentrations in aqueous solutions w
hile t
he same is explained in CCl
4 solutions as due to weakening of t
he strengt
h of solute association. T
he calculation of concentration fluctuation parameter
N
hs/BDA.GIF>(Δx)2
hs/BEA.GIF> indicates t
hat considerable micro
heterogeneity exists in CCl
4 solutions compared to t
hat in aqueous solutions. T
hese findings are furt
her discussed in terms of
hydrop
hobic
hydration,
hydrop
hobic interactions, and water structural effects as well as in terms of effects of conformational c
haracteristics of 18C6 in presence of solvent media.