While interest in investigating chirality and oligomeric species within organic aerosols has grown, a lack of authentic standards limits our capabilities to probe oligomer formation, physical properties, and their overall role in atmospheric processes. Thus, our efforts to synthesize such compounds is motivated by the need for these standards within the atmospheric chemistry community. With a focus on α-pinene-derived oligomeric species putatively identified in ambient secondary organic aerosol particles, and as a first step towards investigating complex oligomers, we report herein the synthesis and evaluation of α-pinenederived dimers formed by the homocoupling or cross-coupling of stereochemically defined monomers by either an aldol reaction or esterification process (Figure ). Subsequent measurements of the interfacial tension depression propensity of our standards, coupled to octanol-water and octanol-ammonium sulfate partitioning coefficient measurements, establish, for the first time, a dependency of cloud activation potential on backbone stereochemistry. products derived from α-pinene react with each other through so-called accretion reactions to form complex dimeric and oligomeric species that constitute significant quantities of material present within secondary atmospheric aerosol particles. For enantiomerically-pure monomers these growth processes will form homochiral products (i.e., scenarios I and II) whose backbone are derived from a single source of chirality (i.e., blue reacts with blue and red reacts with red). In contrast, for racemic or scalemic mixtures of monomers, accretion reactions may take place between molecules derived from the same enantiomeric form of α-pinene (i.e., as in scenarios I and III) or between molecules derived from the opposite enantiomers of α-pinene (i.e., scenario II where blue reacts with red). For this more complicated sequence of reactions, the corresponding dimers and oligomers formed may possess backbones of mixed chiral origin.