An ultra-stable hafnium phosphonate MOF platform for comparing the proton conductivity of various guest molecules/ions.

A porous hafnium-phosphonate MOF was synthesized using imidazole ionic liquids (ILs), namely PHOS-100(Hf), which has exceptional chemical stability in aqueous environments, even fuming acids. Its rigid framework with permanent porosity makes PHOS-100 an ideal candidate as a platform to fill with different functional guests such as acidic HCl, H2SO4, or H3PO4. The as-synthesized ILs@PHOS-100 exhibits significant humidity-dependent proton conductivities, increasing by four orders of magnitude from 45% RH to 95% RH at 25 °C. After post-treatment with strong acids, the acids@PHOS-100 show enhanced proton conduction at low relative humidities.

Polymorphic layered copper phosphonates: exfoliation and proton conductivity studies.

Three polymorphic copper carboxylate-phosphonates are reported, namely, α-Cu(4-cnappH)(H2O) (α-Cu-1), α-Cu(4-cnappH)(H2O)·0.5H2O (α-Cu-2) and ß-Cu(4-cnappH)(H2O) (ß-Cu), where 4-cnappH3 is (4-carboxynaphthalen-1-yl)phosphonic acid. All show layer structures but with different layer topologies. The layer topologies of the α-phases are similar, where the distorted {CuO4} planes and {PO3C} tetrahedra are corner-shared forming an inorganic layer containing 8- and 16-member rings. In ß-Cu, double chains made up of corner-sharing {CuO5} and {PO3C} are crossed-linked through edge-sharing of the {CuO5} square pyramids to form an inorganic layer containing 4- and 8-member rings. The uncoordinated carboxylate groups are protonated and are involved in the interlayer hydrogen bonds in all cases. Antiferromagnetic interactions are dominant in all cases. Compounds α-Cu-1, α-Cu-2 and ß-Cu can be exfoliated in THF resulting in 2D nanosheets of mainly two-layer thickness. Proton conductivity measurements reveal that the proton conduction is more favorable in α-Cu-2 than in α-Cu-1, but exfoliation into nanosheets decreases the conductivity.

Homochiral iron(ii)-based metal-organic nanotubes: metamagnetism and selective nitric oxide adsorption in a confined channel.

Homochiral iron(ii)-based nanotubular metal phosphonates (R)- and (S)-[Fe(pemp)(H2O)2] [pemp2- = (R)- or (S)-(1-phenylethylamino)methylphosphonate] are reported showing metamagnetism at low temperature. The dehydrated product features coordinatively unsaturated and redox-active metal ion sites that enable it to strongly bind nitric oxide at room temperature.

Changes in magnetic order through two consecutive dehydration steps of metal-phosphonate diamond chains.

Hydrothermal reactions of the multitopic ligand 1-hydroxy-1-(piperidin-4-yl)methylidenebisphosphonic acid (hpdpH4) with cobalt or nickel sulfates afforded two new isostructural metal phosphonates, M3 II(hpdpH)2(H2O)6·4H2O [M = Co (Co-10H2O), Ni (Ni-10H2O)]. Their structures consist of parallel diamond chains of three MO6 octahedra bridged by the PO3C tetrahedra. Six of the seven oxygen atoms of the ligand are involved in coordination; for two ligands that amounts to 12 bonds for 3 MO6 and the remaining six are occupied by terminal water molecules. In addition, four water molecules sit in between the chains providing H-bonds to the formation of a 3D-net. Thermal analyses show identical two-step dehydration processes involving first the departure of six water molecules followed by the remaining four. A detailed study of the ac- and dc-magnetization as a function of temperature, field and frequency reveals associated drastic changes. The virgin form Co-10H2O is a paramagnet while its partial dehydrated form Co-4H2O is an antiferromagnet displaying canting below T N = 4.7 K and the fully dehydrated form Co is a ferrimagnet (T C = 12 K). Ni-10H2O and Ni-4H2O exhibit long-range ordered antiferromagnetism (T N = 2.7 and 4.0 K, respectively) and also become ferrimagnets (T C = 9.4 K) when fully dehydrated to Ni. The dehydrated samples can be fully rehydrated with the complete recovery of both the structures and magnetic properties.

Formation Mechanism and Reversible Expansion and Shrinkage of Magnesium-Based Homochiral Metal-Organic Nanotubes.

Two pairs of homochiral magnesium phosphonates, namely (R)-, (S)-[Mg(pemp)(H2 O)2 ] (1) and (R)-, (S)-Mg10 (pemp)10 (H2 O)10 ]⋅3 H2 O (2) are reported (pemp2- =(R)- or (S)-(1-phenylethylamino) methylphosphonate). Compounds 1 show one-dimensional tubular structures. The tube wall is purely inorganic, containing six-membered rings made up of corner-sharing {MgO5 N} octahedra and {PO3 C} tetrahedra. The organic groups reside outside the tube. A bottom-up "direct growing" mechanism is proposed for the formation of the nanotubular structures of 1, based on the electrospray ionization mass spectrometry studies. Compounds 2 display two-dimensional layered structures containing cross-linked squashed nanotubes. Interestingly, the two structures can interconvert reversibly upon temperature and pH modulation. This is the first report of a metal-organic nanotube that can shrink and recover in a reversible manner.

Enantiopure phosphonic acids as chiral inducers: homochiral crystallization of cobalt coordination polymers showing field-induced slow magnetization relaxation.

This Communication reports, for the first time, that enantiopure phosphonic acids can serve as chirality-inducing agents towards homochiral coordination polymers. Hence homochiral chain compounds (M)- or (P)-Co(SO4)(1,3-bbix)(H2O)3 (1M or 1P) are obtained successfully using an achiral precursor of 1,3-bis((1H-benzo[d]imidazol-1-yl)methyl)benzene (1,3-bbix) in the presence of a catalytic amount of (S)- or (R)-3-phenyl-2-((phosphonomethyl)amino)propanoic acid [(S)- or (R)-2-ppapH3]. Furthermore, compound 1M provides the first example of homochiral cobalt compounds showing field-induced single ion magnet behavior.

Racemic cobalt phosphonates incorporating flexible bis(imidazole) co-ligands.

By incorporating flexible bis(imidazol-1-ylmethyl)benzene (bix) co-ligands, four new racemic cobalt phosphonates with formulae Co3(3-ppap)2(1,4-bix)2(H2O)4·4H2O (1), Co3(3-ppap)2(1,3-bix)2(H2O)4·5H2O (2), Co3(3-ppap)2(1,2-bix)2(H2O)4·4H2O (3) and Co3(ppa)2(1,2-bix)2·4H2O (4) are isolated, where 3-ppapH3 represents 3-phenyl-3-((phosphonomethyl)amino)propanoic acid and ppaH3 is 2-phenyl-2-(phosphonomethylamino)acetic acid. Compounds 1-3 crystallize in the monoclinic space group P21/c and show two-dimensional structures in which the Co3(3-ppap)2 chains are bridged by 1,4-bix, 1,3-bix and 1,2-bix ligands in trans-modes, respectively. Within the chain, a racemic dimer of Co2(3-ppap)2(2-) is found, where the Co atoms are doubly bridged by O-P-O units from the (S)- and (R)-3-ppap(3-) ligands. The dimers are connected by another crystallographically independent Co atom through O-P-O linkages to form an infinite racemic chain. The packing modes of the layers in 1-3 are quite different, however, which are ABAB in the cases of 1 and 3 while ABCDABCD in the case of 2, attributed to the positional isomerism of the bix co-ligands. Compound 4 displays a chain structure in which the 1,2-bix bridges the Co atoms in cis-mode within the chain. Magnetic properties are investigated for all compounds.

Chirality- and pH-Controlled Supramolecular Isomerism in Cobalt Phosphonates and Its Impact on the Magnetic Behavior.

Two pairs of enantiomeric compounds with formulas (S)- or (R)-Co3 (ppap)2 (4,4'-bpy)2 (H2 O)2 ⋅4 H2 O [(S)-1 or (R)-1], (S)- or (R)-Co3 (ppap)2 (4,4'-bpy)2 (H2 O)2 ⋅3 H2 O [(S)- or (R)-2), and related racemic compound Co3 (ppap)2 (4,4'-bpy)2 (H2 O)2 ⋅4 H2 O (rac-3; 4,4'-bpy=4,4'-bipyridine, H3 ppap=3-phenyl-2-[(phosphonomethyl)amino]propanoic acid) are reported. Compounds 1 and rac-3 show identical three-dimensional framework structures, whereas compounds 2 have two-dimensional layer structures. Compounds 1 and 2 are catenation isomers, formation of which is controlled solely by the pH of the reaction mixtures, whereas the formation of isomeric compounds 1 and rac-3 is controlled purely by the chirality of the phosphonate ligand. The magnetic properties of fully dehydrated (S)-1, (S)-2, and rac-3 are highly dependent on both structure and chirality.

Homochiral metal phosphonate nanotubes.

A new type of homochiral metal-organic nanotubular structures based on metal phosphonates are reported, namely, (R)- or (S)-[M(pemp)(H2O)2][M = Co(II) (1), Ni(II) (2)] [pemp(2-) = (R)- or (S)-(1-phenylethylamino)methylphosphonate]. In these compounds, the tube-walls are purely inorganic, composed of metal ions and O-P-O bridges. The cavity of the nanotube is hydrophilic with one coordination water pointing towards the center, while the outer periphery of the nanotube is hydrophobic, decorated by the phenylethyl groups of pemp(2-). The thermal stabilities, adsorption and proton conductivity properties are investigated.

pH-controlled polymorphism in a layered dysprosium phosphonate and its impact on the magnetization relaxation.

Two polymorphic layered dysprosium phosphonates α-Dy(2-qpH)(SO4)(H2O)2 (α-Dy) and ß-Dy(2-qpH)(SO4)(H2O)2 (ß-Dy) (2-qpH2 = 2-quinolinephosphonic acid) which crystallize in monoclinic P21/c and triclinic P1̄ space groups, respectively, are reported. Both exhibit field-induced slow relaxation of magnetization at low temperature. The energy barrier for ß-Dy is nearly three times that for α-Dy, attributed to the structural differences in the two phases.

(meso-5,7,7,12,14,14-Hexamethyl-1,4,8,11-tetra-azacyclo-tetra-deca-4,11-diene)copper(II) bis-[O,O'-bis-(4-methyl-phen-yl) dithio-phosphate].

The title compound, [Cu(C(16)H(32)N(4))](C(14)H(14)O(2)PS(2))(2) or [Cu(trans[14]dien)][S(2)P(OC(6)H(4)Me-4)(2)](2), where trans[14]dien is meso-5,7,7,12,14,14-hexa-methyl-1,4,8,11-tetra-azacyclo-tetra-deca-4,11-diene, was obtained by the reaction of [Cu(trans[14]dien)](ClO(4))(2) and [(C(2)H(5))(2)NH](2) [S(2)P(OC(6)H(4)Me-4)(2)](2). The Cu(II) atom lies on a centre of inversion and possesses a relatively undistorted square-planar coordination arrangement with four N atoms of the macrocyclic tetra-mine trans[14]dien [Cu-N = 1.9716 (19) and 2.0075 (19) Å]. The two uncoordinated [(4-MeC(6)H(4)O)(2)PS(2)](-) groups act as counter-ions to balance the charge and inter-act with the [Cu(trans[14]dien)](2+ )complex cation through N-H⋯S hydrogen bonds.

(5,7,7,12,14,14-Hexamethyl-1,4,8,11-tetra-aza-cyclo-tetra-deca-4,11-diene)nickel(II) bis-[O,O'-bis-(4-tert-butyl-phen-yl) dithio-phosphate].

The title salt, [Ni(C(16)H(32)N(4))](C(20)H(26)O(2)PS(2))(2), comprises a centrosymmetric [Ni(Me(6)[14]dieneN(4))](2+) dication (Me(6)[14]dieneN(4) is 5,7,7,12,14,14-hexa-methyl-1,4,8,11-tetra-aza-cyclo-tetra-deca-4,11-diene) and two O,O'-bis-(4-tert-butyl-phen-yl) dithio-phosphate anions. The Ni(II) ion lies on an inversion centre and displays a slightly distorted NiN(4) square-planar chelation arrangement with four N atoms from the Me(6)[14]dieneN(4) macrocycle. Two S atoms from symmetry-related anions are located in pseudo-axial positions with respect to the Ni(II) ion, with Ni⋯S distances of 3.2991 (7) Å. Inter-molecular N-H⋯S and C-H⋯S hydrogen bonds link the complex cation and pair of anions into a 1:2 type salt.

(meso-5,5,7,12,12,14-Hexamethyl-1,4,8,11-tetra-aza-cyclo-tetra-deca-ne)nickel(II) bis-[O,O'-bis-(4-methyl-phen-yl) thio-phosphate].

In the centrosymmetric title complex, [Ni(C(16)H(36)N(4))](C(14)H(14)O(3)PS)(2), the Ni(II) ion is coordinated by four N atoms and two O atoms within a slightly distorted NiN(4)O(2) octa-hedral geometry. The asymmetric unit consits of one Ni(II) ion that is located on a center of inversion, half of the macrocylic ligand and one anion occupying general positions. Intra-molecular N-H⋯O and N-H⋯S hydrogen bonding is found between the macrocyclic ligand and the monothio-phosphate anion.

(C-meso-N-meso-5,12-Dimethyl-7,14-diphenyl-1,4,8,11-tetra-aza-cyclo-tetra-deca-4,11-diene)copper(II) bis-[O,O'-bis-(4-methyl-phen-yl)dithio-phosphate].

In the title compound, [Cu(C(24)H(32)N(4))](C(14)H(14)O(2)PS(2))(2), the Cu(II) atom lies on an inversion center and is chelated by the macrocyclic ligand in a distorted CuN(4) square-planar geometry. Two O,O'-bis-(4-methyl-phen-yl)dithio-phosphate anions occupy the axial positions with long Cu⋯S distances of 3.0090 (8) Å. Inter-molecular N-H⋯S and C-H⋯S hydrogen bonding is present between the anions and the cation.

(meso-5,5,7,12,12,14-Hexamethyl-1,4,8,11-tetra-aza-cyclo-tetra-deca-ne)copper(II) bis-[O,O'-(o-phenyl-ene)dithio-phosphate].

In the title compound, [Cu(C(16)H(36)N(4))](C(6)H(4)O(2)PS(2))(2), the Cu(II) cation lies on an inversion center and is chelated by the macrocyclic tetra-amine ligand in a slightly distorted CuN(4) square-planar geometry. The axial positions are occupied by two O,O'-(o-phenyl-ene)dithio-phosphate anions with long Cu⋯S distances of 3.0940 (7) Å. Inter-molecular N-H⋯S and C-H⋯O hydrogen bonding is present between the anions and the cation and helps to stabilize the crystal structure.

(C-meso-N-meso-5,12-Dimethyl-7,14-diphenyl-1,4,8,11-tetra-aza-cyclo-tetra-deca-4,11-diene)nickel(II) bis-[O,O'-bis-(4-methyl-phen-yl) dithio-phosphate].

The title complex, [Ni(C(24)H(32)N(4))](C(14)H(14)O(2)PS(2))(2), comprises a centrosymmetric [Ni(meso-diphen-yl[14]dien)](2+) dication (meso-diphen-yl[14]dien is C-meso-N-meso-5,12-dimethyl-7,14-diphenyl-1,4,8,11-tetra-aza-cyclo-tetra-deca-4,11-diene) and two O,O'-bis-(4-methyl-phen-yl) dithio-phosphate anions. The Ni(II) ion lies on an inversion center and is chelated by a tetra-amine macrocycle ligand in a slightly distorted NiN(4) square-planar geometry. Two S atoms from symmetry-related anions are located in pseudo-axial positions with respect to the Ni(II) ion, with Ni⋯S distances of 3.1869 (8) Å. In the crystal, bifurcated inter-molecular N-H⋯S(S) hydrogen bonds connect cations and pairs of anions into three-component clusters. Weak inter-molecular C-H⋯S hydrogen bonds link these clusters into chains along [100].

(meso-5,5,7,12,12,14-Hexamethyl-1,4,8,11-tetra-azacyclo-tetra-deca-ne)copper(II) bis-(O,S-dibenzyl dithio-phosphate).

In the crystal structure of the title compound, [Cu(C(16)H(36)N(4))](C(14)H(14)O(2)PS(2))(2), the Cu(II) atom is located on an inversion center and is chelated by four N atoms of the macrocyclic meso-5,5,7,12,12,14- hexa-methyl-1,4,8,11-tetra-azacyclo-tetra-decane ligand in a square-planar geometry, with Cu-N distances of 2.013 (3) and 2.014 (3) Å. In the crystal structure, one O,S-dibenzyl dithio-phosphate counter-anion links with the Cu(II) complex cation through N-H⋯O and N-H⋯S hydrogen bonding. During the synthesis, the structure of the anion re-arranged from O,O'-dibenzyl dithio-phosphate in the starting material to O,S-dibenzyl dithio-phosphate in the title compound.

(meso-5,5,7,12,12,14-Hexamethyl-1,4,8,11-tetra-azacyclo-tetra-deca-ne)nickel(II) bis-(O,O'-dibenzyl dithio-phosphate).

In the title salt-type 1:2 adduct, [Ni(C(16)H(36)N(4))](C(14)H(14)O(2)PS(2))(2) or [Ni(tet-a)][S(2)P(OCH(2)Ph)(2)](2), where tet-a is meso-5,5,7,12,12,14-hexa-methyl-1,4,8,11-tetra-azacyclo-tetra-decane, the [Ni(tet-a)](2+) complex cation exhibits a relatively undistorted square-planar geometry about the Ni atom, which lies on an inversion centre and is coordinated by four macrocyclic N atoms. The two O,O'-bis-(2-phenyl-meth-yl) dithio-phosphate anions act as counter-ions to balance the charge and they inter-act with the complex through N-H⋯S hydrogen bonds. Important geometric data include Ni-N distances of 1.958 (3) and 1.963 (3) Å.

Bis(O,O'-diphenethyl dithio-phosphato-κS,S')bis-(4-methyl-pyridine-κN)nickel(II).

The title complex, [Ni(C(16)H(18)O(2)PS(2))(2)(C(6)H(7)N)(2)], exhibits a roughly octa-hedral coordination geometry. The Ni(II) atom lies on an inversion centre and is coordinated by four S atoms of O,O'-diphenethyl dithio-phosphate mol-ecules and two N atoms of 4-methyl-pyridine mol-ecules. Important geometric data include Ni-N = 2.100 (3) Å, and Ni-S = 2.5101 (10) and 2.4772 (11) Å.