Photocatalytic Properties and Luminescent Sensing for Cr³⁺ Cations of Polyoxovanadates-Based Inorganic–Organic Hybrid Compounds with Multiple Lewis Basic Sites

A new family of polyoxovanadates-based inorganic–organic hybrid compounds with multiple Lewis basic sites, namely, [Zn 5 (Htrb) 2 (H 2 O) 2 (V 5 O 15 ) 2 ]·11H 2 O ( 1 ), [Zn 2 (Htrb)(HV 5 O 15 )]·6H 2 O ( 2 ), [Co 3 (Htrb)(H 2 O) 4 (V 3 O 9 ) 2 ]·4H 2 O ( 3 ), and [Ag 3 (Htrb)(H 4 V 5 O 16 )]·H 2 O ( 4 ), have been hydrothermal synthesized by using a multidentate N-containing hexakis(1,2,4-triazol-ylmethy1)benzene (Htrb). In 1, [V 4 O 12 ] 4– and [V 6 O 18 ] 6– rings are linked by Zn(II) ions into a two-dimensional (2D) inorganic layer, which are pillared by Htrb ligands to afford a unique three-dimensional (3D) framework. In 2, rod-shaped [H 2 V 10 O 30 ] 8– clusters are bridged by Zn(II) ions to generate one-dimensional inorganic hybrid motifs, which are joined by Htrb ligands to yield a 3D framework. In 3, Co(II) ions bridge [V 6 O 18 ] 6– rings to result in a 2D inorganic sheet, and the adjacent sheets are extended by the Htrb ligands into a 3D motif. In 4, adjacent 12-membered vanadium rings, composed of [VO 4 ] tetrahedra and [VO 5 ] trigonal bipyramids, form a unique 2D inorganic layer via sharing corner O atoms. Strikingly, neighboring layers are further extended by Htrb ligands and Ag(I) ions into a 3D framework. Moreover, photocatalytic degradation of compounds 1, 3, and 4 toward methylene blue (MB) and methyl orange (MO) was studied under UV light irradiation. A possible photocatalytic mechanism was also speculated by introducing t -butyl alcohol as a widely used · OH scavenger. In addition, luminescent selective and sensitive sensing of Cr 3+ compared with other metal ions such as Zn 2+, Al 3+, Co 2+, K +, Na +, and Pb 2+ were investigated by using 1 and 4 . Finally, their electrochemical behaviors were also studied.