The present invention provides a new class of organic/inorganic hybrid materials having [ER]n rings interconnected by E′ atoms. In an embodiment a class of materials called high organic group content periodic mesoporous organosilicas (HO-PMO's) with [SiR]3 rings interconnected by O atoms is described. The measured dielectric, mechanical and thermal properties of the materials suggest that an increased organic content achieved by the [SiR]3 rings of a high organic group content periodic mesoporous organosilica leads to superior materials properties potentially useful for a wide range of applications including microelectronics, separation, catalysis, sensing, optics or electronic printing.