Hydrophobic-exterior layer structures and magnetic properties of trinuclear copper complexes with chiral amino alcoholate ligandsElectronic Supplementary Information (ESI) available: X-ray powder diffractograms, IR spectra, H-bonding details, packing diagrams, photographs of experimental setups. CCDC reference numbers 864924-864928. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c2nj40063d

• Main Authors: Maclaren, Jana K, Sanchiz, Joaquín, Gili, Pedro, Janiak, Christoph
• Format: Article
• Language: English
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/c2nj40063d

The trinuclear secondary building unit (SBU) {Cu 3 (-L) 4 X 2 } constructed from chelating and alcoholate- O -bridging chiral amino alcoholate (amino alkoxido, -L) and terminal halide ligands (X) gives rise to two-dimensional (2D) homochiral supramolecular polymers through the bridging action of the halide ligand. Compounds 2D-[Cu 3 (-L) 4 ( 3 -X) 2 ] {X = Br ( 1 to 4 ), X = Cl ( 5 , 6 ); L = amino-ethanolate ( 1 , 5 ), ( R )-2-amino-propan-1-olate ( 2 ), ( R )-2-amino-butan-1-olate (ab) ( 3 , 6 ), ( R )-2-amino-2-phenyl-ethanolate ( 4 )} were synthesized from 2-amino alcohol, LH with CuBr 2 or CuCl 2 , respectively, in the presence of triethylamine (TEA). The crystal packing of isomorphous 2D-[Cu 3 (-L) 4 ( 3 -X) 2 ] shows a separation of the hydrophobic alkyl from the hydrophilic amino-/alcoholate-/Cu-Br-region. Charge-assisted Cu (2+) () Br- and hydrogen-bonding interactions in the hydrophilic region are the driving force of "hydrophobic exterior layer" formation with a hydrophilic interior exposing the hydrophobic alkyl groups to the exterior. Stacking of the layers through weak van-der-Waals interactions between the alkyl groups correlates with formation of thin crystal plates along the stacking direction. A lower ligand concentration yields both dinuclear and mononuclear SBUs in one-dimensional (1D-) homochiral coordination polymers 1D-[{Cu 2 (-ab) 2 Br 2 } 2 {( 3 -Br)Cu(abH) 2 Br}{( 3 -Br)Cu(abH)(CH 3 OH)Br}] ( 7 ) and 1D-[{Cu 2 (-ab) 2 Cl 2 } 2 {( 3 -Cl)Cu(abH)(CH 3 CH 2 OH)Cl} 2 ] ( 8 ). In {[Cu( rac- abH)( rac- ab)H 2 O]ClO 4 } 2 ( 9 ) two SBUs combine through charge assisted H-bonds to a dimeric unit. Temperature dependent magnetic susceptibility measurements of 1 and 3 show ferromagnetic coupling but no magnetic ordering. However, at temperatures lower than 3 K an onset of long-range magnetic ordering can be observed. AC magnetic measurements in the range of 1.9 K to 5 K at different frequencies show that the long range magnetic ordering is achieved at lower temperatures than that. Correlation of magnetic coupling with the Cu-O-Cu angle is in agreement with the structural parameters of 1 and 3 . Very good agreement between experimental and DFT calculated J , j coupling constants shows that the interaction between the terminal copper( ii ) ions in these linear trinuclear SBUs is operative and it cannot be neglected. Charge-assisted Cu (2+) () Br- and H-bonding interactions in the hydrophilic region are the driving force of "hydrophobic exterior