Exfoliated single layer cadmium phosphorus trisulphide has been combined with the biological molecule adenosine monophosphate (AMP) to form the novel restacked compound LixCd0.8PS3(AMP)(z)(H2O)(y). Composition was determined using energy dispersive X-ray spectroscopy, and the structure of these compounds was studied using X-ray diffraction on oriented films. In the 0-80% relative humidity range, for (AMP)(0.5), a host plane spacing near 19.6 angstrom was found. Electron density calculations based on the X-ray diffraction pattern suggest a model for the arrangement of guest AMP molecules between the host layers, with an accompanying water molecule. The calculations also suggest that there is a buckling in the host layer of about +/- 0.6 angstrom. (c) 2005 Elsevier Ltd. All rights reserved.