Spin liquids are phases of matter where, in spite of strong near neighbour magnetic interactions, long range magnetic ordering is prevented due to conflicting interactions. Geometric frustration acts as one of the driving mechanisms to realize Quantum Spin Liquids (QSL) in actual materials. The low-energy physics of QSL is interesting and they are believed to host novel, emergent quasiparticles (possibly obeying fractional statistics)! Therefore, exploration to find new QSL is an important activity touching upon fundamental physics aspects. In the title systems, the (111) planes contain edge shared triangles with Cu at the vertices. Our bulk and NMR data show absence of LRO or glassy behaviour down to 0.5 K in spite of strong interactions. We propose muSR as a local probe of dynamics of local moments to check for spin liquid behaviour.