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organic compounds
The crystal structure of the complex of (−)-morphine with (S)-β-phenylhydracrylic acid, C17H20NO3+.C9H9O3−, is reported. There are no major differences in the conformation of the piperidine ring of morphine compared with other protonated morphines. The staggered conformation of the central bond in the free form of β-phenylhydracrylic acid changes to another staggered conformation in the morphine complex. This conformational change is induced by intermolecular hydrogen bonds.