Weak C-H···O hydrogen bonds in anisaldehyde, salicylaldehyde and cinnamaldehyde.

In situ cryocrystallization has been employed to grow single crystals of 4-meth­oxy­benzaldehyde (anisaldehyde), C8H8O2, 2-hy­droxy­benzaldehyde (salicyl­aldehyde), C7H6O2, and (2E)-3-phenyl­prop-2-enal (cinnamaldehyde), C9H8O, all of which are liquids at room temperature. Several weak C—H⋯O inter­actions of the types Caryl—H⋯O, Cformyl—H⋯O and Csp3—H⋯O are present in these related crystal structures.