The structural, optical and related properties (i.e. photoluminescence, photoconductivity etc) of some synthetic (i.e. unconventional) three- and lower-dimensional semiconductor systems, which are based on inorganic units (:metal-halides, metal-chalcogenides etc), are briefly reviewed and some new results are reported. A blue shift of the excitonic bands as well as enhancements of their binding energy and intensity were observed by decreasing the dimensionality or the size of the materials active part. The results are similar to those obtained from conventional semicomductors, such as GaAs, CdS, PbI2, by decreasing the dimensionality or the size.