Crystallization cleavage-induced

To be clear, the phenomenon of cleavage-induced crystallization should not be confused with solvent-induced crystallization, in which mobility is increased by the lowering of the glass transition temperature. We are also not referring to the well-known effect of molecular weight on mobility and hence crystallizability. Instead, it is based on removing a physical restraint of the molecular chain. 

Patra AK, Nethaji M, Chakravarty AR. Synthesis, crystal structure, DNA binding and photo-induced DNA cleavage activity of (.S -mcthyl-r.-cystcinc)coppcr(II) complexes of heterocyclic bases. J Inorg Biochem 2007 101 233-44. 

Since both amino and bulky substituents are known to stabilize cycloprope-nium salts [20], we chose to investigate the Lewis-acid induced P-N bond cleavage of the phosphaalkene 9, which is readily synthesized from the corresponding bis(phosphino)diazomethane 8 [21]. Indeed, treatment of 9 with two equivalents of BF3.Et2NH complex at room temperature afforded diphosphirenium salt 2 Pa as non-air sensitive pale-yellow crystals (mp 118°C) in 60% yield [22a] (Scheme 6). Subsequently, we found that using BF3.Et20 in the place of... 

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