Bacteriochlorophyll (BChl) c is a major light-harvesting pigment family in green photosynthetic bacteria. In organic solvents, the pigment molecules are capable of forming stable dimers and self-assembling into high aggregates which have been used as a model for the native chlorosome antenna. NMR relaxation times were measured for the intact farnesyl (3(1)R)-[E, E]BChl c(F) in methanol, acetone, and carbon tetrachloride. The spin-lattice relaxation times (T-1(H)) were determined to be 0.3-1.2 s for the macrocyclic protons and 0.73-3.3 s for the farnesyl protons in methanol and acetone in which the BChl c exists as a monomer. Strong hydrogen bonding between the BChl c and solvent molecules resulted in a significant reduction in the spin-spin relaxation times (T-2(H)) for the protons close to the hydrogen-bonding sites. This result can be interpreted in terms of a combined effect of scalar coupling with the hydroxyl proton and dipolar interaction with the solvent molecules. Formation of BChl c dimer in carbon tetrachloride led to an increase in T-1(H) and a large decrease in T-2(H) with respect to the values of monomer, indicating that the correlation time became longer as a result of the much reduced molecular motion. With the use of a highly randomly C-13-labeled sample, we were able to measure the C-13 relaxation times. The T-1(C) were determined in a range of 0.26-3.3 s for the macrocyclic carbons in methanol, and these values decreased as BChl c formed a dimer but remained in the same order of magnitude. The (3(1)R)-[E, E]BChl c(F) is demonstrated as an ideal molecule for studying the hydrogen-bonding property and the dynamic exchange behavior between the individual molecules within a dimer.