The
solvothermal reaction of Mn(ClO<sub>4</sub>)<sub>2</sub>, NaN<sub>3</sub>, and a rigid viologen-tethered tetracarboxylic acid (1,1′-bis(3,5-dicarboxyphenyl)-4,4′-bipyridinium
chloride, [H<sub>4</sub>L]Cl<sub>2</sub>) led to a coordination polymer
of formula [Mn<sub>4</sub>(L)(N<sub>3</sub>)<sub>6</sub>(H<sub>2</sub>O)<sub>2</sub>]<sub><i>n</i></sub>. X-ray analysis
revealed a 3D coordination structure. The Mn(II) ions are connected
by mixed azide and carboxylate bridges to give 2D layers, which are
pillared by the viologen tether of the zwitterionic ligand. Magnetic
analyses suggested that the compound features antiferromagnetism and
field-induced metamagnetism. The compound also shows photochromic
and photomagnetic properties. The long-range magnetic ordering is
owed to the spin-canting structure of the Mn(II)-azide-carboxylate
layer; the photochromism involves the formation of viologen radicals
via photoinduced electron transfer, and the photomagnetism is related
to the interactions between the metal ion and the photogenerated radicals.
The study demonstrates a strategy for the design of new multifunctional
materials with photoresponsive properties