  Many bent-core nematic liquid crystals exhibit unusual physical properties
due to the presence of smectic clusters, known as "cybotactic" clusters in the
nematic phase. Effect of these clusters on complex shear modulus
($G^*(\omega)$) of such liquid crystals hitherto unexplored. Here, we study
flow viscosities and complex shear modulus of two asymmetric bent-core liquid
crystals using microrheology technique. The results are corroborated with the
measurements of curvature elastic constants. Compound with shorter hydrocarbon
chain (8OCH$_\text{3}$) exhibit only nematic (N) phase whereas the compound
with longer chain (16OCH$_\text{3}$) exhibits both nematic (N) and smectic-A
(SmA) phases. Our results show that the directional shear modulus of
16OCH$_\text{3}$, just above the SmA to N transition temperature is strikingly
different than 8OCH$_\text{3}$, owing to these smectic clusters. Thus,
microrheology enables us to probe smectic clusters in bent-core nematic liquid
crystals.
