Using periodic ab initio quantum mechanical calculations, we have investigated 16 low-valence dopant ions isomorphously substituted in the framework of the zeolite chabasite and of its isostructural aluminophosphate, AIPO-34. The low-valence ions are charge balanced by one acid proton. We have determined the stretching frequency of the acid OH group in each material, and examined its correlation with the structural and electronic parameters of the dopant ions. Results show that the behavior of zeolites and AIPOs is complex; optimization of their properties is suitable to combinatorial chemistry approaches, to which computational studies can make a substantial contribution.