Photophysical properties of donor-∏-acceptor azoic chromophores adsorbed and intercalated into MgAlLDH

Ethyl Orange (EO) and 4-aminoazobenzene-4-sulfonic (AS) anions with Donor-∏-Acceptor structure have been intercalated into the layered double hydroxide (LDH), [Mg0.66 Al0.34 (OH)2] (CO3)0.17·0.67H2O or adsorbed on the external surface of the host by the method of ion-exchange procedures. The photoabsorption and fluorescence properties of the obtained compounds were different from the pure solid phase of EO and AS. It was suggested that the photophysical properties of guests were closely related to the geometry and electrical structure of the guest molecule, which can affect the distribution and orientation of the guests in the layers or on the surface of the host. The host–guest interactions modulate photophysical properties of guest. In addition, the guest having higher molecular dipole moments surface exchanged on MgAlCO3LDH are beneficial to the enhancement of the blue emission than that of intercalation into LDH.

Emission spectra of (a) EO (b) EO surface exchanged on MgAlCO3LDH (c) MgAlEOLDH. Emission spectra of (a) AS (b) MgAlASLDH (c) AS surface exchanged on MgAlCO3LDH. The guests having higher molecular dipole moments surface exchanged on MgAlCO3LDH are beneficial to the enhancement of the blue emission than that of intercalation into LDH.Figure optionsDownload as PowerPoint slideHighlights
► EO and AS are intercalated into LDHs or adsorbed on the external surface of LDHs.
► The host–guest interactions modulate photophysical properties of the guest.
► The guests having higher molecular dipole moments can enhance the blue emission.