The rational design and synthesis of organic templates for the synthesis of new microporous materials has resulted in the production of five new materials, three of which are known to be microporous, the other two being better described as being open framework materials. The first three microporous materials are named STA-1, -2 and -3 (for St. Andrews) and have structural compositions of the form MgxAl1-xPO4 x/n Rn+.yH2O (Mg0.18Al0.82PO4.R0.094-0.22H2O, as determined by EDX for STA-1). The fourth novel microporous solid is a boron aluminophosphate (BAlPO) and the fifth an aluminophosphate solid containing its organic template intact. All of the new materials were synthesised following a systematic study over a wide range of templates including 5 homologous series designed specifically to be used as templates in the production of alumino-silicates and -phosphates. The structure of the first two magnesium aluminophosphates (STA-1, STA-2) to be solved by single microcrystal diffraction at the ESRF at Grenoble on crystals approximately 30 x 30 x 30 mum in size is described. The in situ location of the template was determined directly from x-ray diffraction in the second of these materials and has formed part of a combined experimental and computational study into template location within novel frameworks. The study shows how the encapsulation of the template is directly responsible for the similarity in pore architecture between MAPO-56 and STA- 2 (which co-crystallise) since the template adopts the same orientation in both materials Polymeric / oligomeric templates have also formed part of this study. These templates are shown to influence the phase, crystallinity, particle size and catalytic performance of the product magnesio-aluminophosphate MAPO-31. Computer modelling has also been utilised to interpret the experimental data obtained from the systematic study on the use of polymeric templates. The in situ synthesis and subsequent encapsulation of two coordination complexes inside the supercage of zeolite-Y, including the 3-methyl-1,3,5,8,12- pentaazacyclotetradecane macrocycle is also described.