Host - guest complex of β -cyclodextrin and dimethyl yellow in aqueous system - A <span style="font-size:12.0pt;font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";mso-ansi-language:EN-IN;mso-fareast-language: EN-IN;mso-bidi-language:AR-SA" lang="EN-IN">spectrophotometric study on solubilization of dimethyl yellow in dilute aqueous solution of <span style="font-size: 12.0pt;font-family:"Times New Roman";mso-fareast-font-family:HiddenHorzOCR; mso-ansi-language:EN-IN;mso-fareast-language:EN-IN;mso-bidi-language:AR-SA" lang="EN-IN">β -cycl<span style="font-size:12.0pt;font-family:"Times New Roman";mso-fareast-font-family: "Times New Roman";mso-ansi-language:EN-IN;mso-fareast-language:EN-IN; mso-bidi-language:AR-SA" lang="EN-IN">odextrin</span></span></span>

Abstract

Solubilization of dimethyl yellow (DMY) in dilute β -cyclodextrin (β-CD ) aqueous solution (the concentration range is from 0 to 9 × <span style="mso-bidi-font-style:italic">10^-3<i> M) </i>have been determined by spectrophotometry at 293.2, 298.2, 303.2, 308.2 and 313.2 K respectively. The results show that DMY and β -CD form host-guest complex of 1:1 stoichiometry. The equilibrium constants <i>(K</i>_{<span style="mso-bidi-font-style:italic">c</span>}^{<span style="mso-bidi-font-style: italic">o</span>}<i>) </i>of the complexing process at the five temperatures are calculated and the thermodynamic parameters (∆<i style="mso-bidi-font-style: normal">G</i>^o, ∆<i style="mso-bidi-font-style:normal">H</i>^{<span style="mso-bidi-font-style:italic">o</span>}<i> </i>and <i>T</i>∆<i>S</i>^{<span style="mso-bidi-font-style:italic">o</span>}<i>) </i>are estimated based on the values of the equilibrium constants. The data indicate that the complexing process is an enthalpy drive one.<span style="font-family:Symbol;mso-ascii-font-family: " times="" new="" roman";mso-hansi-font-family:"times="" roman";mso-char-type:symbol;="" mso-symbol-font-family:symbol"="" lang="EN-IN"><span style="mso-bidi-font-style:italic"></span></span></span>