To　explore　the　influence　of　non-covalent　weak　force　interactions,　mainly　exerted　by　carboxylic　groups,　on　the　formation　of　supramolecular　architectures　of　transition　metal　complexes　and　their　electrical　conduction　processes,　a　new　symmetrical　[N4O2]　hexadentate　Schiff　base　ligand,　1,8-N-bis(3-carboxy)disalicylidene-3,6-diazaoctane-1,8-diamine,　abbreviated　to　H(4)fsatrien,　and　its　complexes　of　Ni(II),　Cd(II)　and　Mn(II)　have　been　synthesized　using　in　situ　condensation　of　the　ligand　components　in　the　presence　of　metal　ions.　The　complexes　were　structurally　characterized　by　elemental　analyses,　IR,　UV-Vis,　NMR.　ESR,　molar　conductivity　and　magnetic　measurements.　The　crystal　structures　of　all　the　complexes　have　been　determined　by　a　single　crystal　X-ray　diffraction　study.　The　1-D,　2-D　and　3-D　networks　of　the　complexes　are　formed　by　pi-pi　stacking,　C-H...pi　interactions　and　mono　or　bifurcated　H-bonding.　The　electronic　structures　of　the　complexes　have　been　examined　using　the　DFT　method.　Solid-state　properties　(e.g.　electrical　conductivity　at　different　temperatures　and　optical　properties)　of　the　Ni(II)　and　Mn(II)　complexes　have　also　been　studied　and,　depending　on　the　temperature,　the　conductivity　of　the　complexes　is　found　to　be　insulating　and　semiconducting　(intrinsic　and　extrinsic)　in　nature.　The　optical　band　gap　(E-gd)　of　complexes　(1)　and　(3)　is　found　to　be　2.57　and　2.30　eV,　respectively.　(C)　2008　Elsevier　Ltd.　All　rights　reserved.