We report on the vibrational population relaxation and rotational diffusion dynamics of 1-methylperylene in a series of branched alkanes with the common formula C7H16. Using the 1370 cm(-1) ring breathing resonance of 1-methylperylene as the donor state and the 1378 cm(-1) methyl rocking resonance of the solvents as the acceptor state, we have found that the T-1 times of 1-methylperylene vary from 10 to 24 ps and the rotational diffusion times in these same solvents range from 10 to 23 ps, but the two relaxation time constants do not correlate directly. For these systems, the time constant for vibrational population relaxation, T-1, is directly proportional to solvent CH3 group density, counter to the expected behavior for a statistical orientational distribution of solvent molecules about the solute. The experimental T-1 times are also inversely proportional to the boiling point of the solvent, indicating that the ability of the solvent to form organized assemblies around the solute determines the coupling between the solute donor mode coordinate and the solvent acceptor vibrational mode. These data indicate that bath density considerations are less important than intermolecular alignment in determining the efficiency of energy transfer over molecular length scales.