The　aqueous　self-assembly　of　the　flexible　ligand　L　bis(1H-benz[d]imidazole-1-yl)methane　and　cis-coordinated　Pt-II　precursors　[(en)Pt2+,　(tmeda)Pt2+,　en=ethylenediamine,　tmeda=N,N,N,N-tetramethylethylenediamine)]　led　to　the　formation　of　the　metallacalixarenes　with　full　alternative　conformations　(e.g.,　two　novel　water-soluble　metallacalixarenes　[M2L2](4+)　and　[M3L3](6+)　with　D-2　and　D-3　symmetry,　respectively).　Their　molecular　structures　were　determined　by　single　crystal　X-ray　analyses　in　solid　state.　The　two　metallacalixarenes　present　different　cavity　sizes　and　the　[M3L3](6+)　cavity　encapsulates　one　NO3-.　NOESY　NMR　revealed　that　the　conformational　interconversion　between　1,3-alternate　conformer　in　methanol　and　cone　conformer　in　DMSO　was　tuned　via　the　synergistic　effect　between　solvent　and　anion.　Guest　encapsulation　is　also　discussed.