A charge-transfer complex of 2,5-dimethyl-N,N'-dicyanoquinonediimine (DM) with silver (crystalline Ag(DM)(2), defined as a) is irreversibly transformed by UV-vis illumination. Depending on the illumination conditions, three new types of solids (defined as gamma, delta, and epsilon) with different structural and physical properties are obtained and examined by a variety of analytical techniques, including solid-state, high-resolution, cross-polarization magic angle spinning (CP-MAS) (CNMR)-C-13, elemental analysis (EA), mass spectrometry (MS), X-ray absorption fine structure (XAFS), and powder X-ray diffraction (XRD). The CP-MAS, EA, MS, and XAFS results indicate that compound gamma is a glass state of Ag(DM)(2). The transformation from crystalline (a) to amorphous (gamma) solid Ag(DM)(2) is an irreversible exothermic glass transition (glass-transition temperature 155.2 degrees C; Delta H=-1.26.8 kJ mol(-1)), which implies that the glass form is thermodynamically more stable than the crystalline form. Compound delta (Ag(DM)(1.5)) consists of silver nanoparticles (diameter (7 +/- 2) nm) dispersed in a glassy matrix of neutral DM molecules, The =N-CN-Ag coordination bonds of the a form are not maintained in the delta form. Decomposition of a by intense illumination results in a white solid (epsilon), identified as being composed of silver nanoparticles (diameter (60 +/- 10) nm). Physical and spectroscopic (XAFS) measurements, together with XRD analysis, indicate that the silver nanoparticles in both delta and epsilon are crystalline with lattice parameters similar to bulk silver; however, the magnetic susceptibilities differ from bulk silver.