How do molecules aggregate in solution, and how do these aggregates consolidate themselves in crystals? What is the relationship between the structure of a molecule and the structure of the crystal it forms? Why do some molecules adopt more than one crystal structure? Why do some crystal structures contain solvent? How does one design a crystal structure with a specified topology of molecules, or a specified coordination of molecules and/or ions, or with a specified property? What are the relationships between crystal structures and properties for molecular crystals? These are some of the questions that are being addressed today by the crystal engineering community, a group that draws from the larger communities of organic, inorganic, and physical chemists, crystallographers, and solid state scientists. This Perspective provides a brief historical introduction to crystal engineering itself and an assessment of the importance and utility of the supramolecular synthon, which is one of the most important concepts in the practical use and implementation of crystal design. It also provides a look to the future from the viewpoint of the author, and indicates some directions in which this field might be moving.

Crystal engineering: from molecule to crystal.

Effects of substituents on the photochemical and photophysical properties of main group metal phthalocyanines

Photodynamic therapy is a binary treatment now accepted in clinic for various malignancies in several countries around the world. Phthalocyanine molecules are second-generation photosensitizers with enhanced photophysical and photochemical properties over those of porphyrins. They have been shown to be phototoxic against a number of cell types and tumor models. A great deal of research has been devoted to the elucidation of their mechanism of action and mode of cell death. The present paper reviews phthalocyanine pre-clinical anti-cancer research with emphasis on phthalocyanine induced apoptosis using a silicon phthalocyanine, Pc4. A brief summary of the latest clinical results using phthalocyanines is presented.

Current status of phthalocyanines in the photodynamic therapy of cancer

In this report, which is complementary to that of Bleaney and Stevens in Reports on Progress in Physics, Volume XVI, paramagnetic resonance data are collected together for crystalline solids containing ions of the transition groups, and those parts of the theory necessary for an understanding of the results are presented in a fairly simple way. After a brief introduction, the magnetic properties of various types of compounds are considered, and a simple discussion is given of the spin Hamiltonian which is used to describe the lowest energy levels. Some details are also given of the structures of the ten crystal types which are most commonly used, and of the relation between the structure and the resonance spectrum of a single crystal. Finally, the resonance data which are available for ions of the 3d, 4d, 5d, 4f and 5f transition groups are tabulated. These data are expressed as values of the parameters in the appropriate spin Hamiltonian, and, where applicable, formulae are given for (1) energy levels, (2) susceptibility, (3) specific heat tail CT2/R, in terms of these parameters.

https://iopscience.iop.org/article/10.1088/0034-4885/18/1/308/pdf

J. Monteath Robertson

Papers

136. An X-ray study of the structure of the phthalocyanines. Part I. The metal-free, nickel, copper, and platinum compounds

72. The crystal structure of pyrene. A quantitative X-ray investigation

518. Crystal-structure studies of polynuclear hydrocarbons. Part I. 2 : 3-8 : 9-dibenzoperylene