Two New Zinc Phosphonates with Triazine-Based Phosphonic Acids

Hydrothermal
reactions of Zn­(CH3COO)2·2H2O with two new triazine-based phosphonic acids, 2,4,6-triglyphosate-1,3,5-triazine
(H9L1) and 4,6-biglyphosate-2-hydroxyl-1,3,5-triazine (H6L2), afforded two new zinc phosphonates, namely, [(C5H14N2)­Zn3(HL1)­(H2O)]·3.5H2O (1) and [(C5H14N2)­Zn2L2]·3H2O (2),
respectively. The two zinc phosphonates were structurally characterized
through single-crystal X-ray diffraction. Compound 1 is
a three-dimensional (3D) framework in that Zn–O–P chains
are connected by HL18– anions with hendecadentate
modes. In compound 2, each L26– anion
links four Zn2 binuclear units to form a 3D framework. In both compounds 1 and 2, the protonated 2-methylpiperazines are
encapsulated into the channels of 3D frameworks. Thermogravimetric
analysis and powder X-ray diffraction reveal that compounds 1 and 2 are thermally stable up to 200 and 160
°C under an air atmosphere, respectively. Compounds 1 and 2 display near-UV and purple luminescence with
maximal bands at 377 and 402 nm, respectively. It worth noting that
the luminescence of solids 1 and 2 can be
preserved after compounds 1 and 2 are heated
at 200 and 160 °C for 2 h under an air atmosphere, respectively.
In addition, the ion-exchange property of compound 1 was
also studied.