Nine metal-organic frameworks have been prepared with the hexagon-shaped linker 1′,2′,3′,4′,5′,6′-hexakis(4-carboxyphenyl)benzene (H6cpb) by solvothermal reactions in dimethylformamide (dmf) or dimethylacetamide (dmac) with acetic acid or formic acid as modulators: [Bi2(cpb)(acetato)2(dmf)2]∙2dmf CTH-6 forms a rtl-net; 2(H2NMe2)[Cu2(cpb)] CTH-7 forms a kgd-net; [Fe4(cpb)(acetato)2(dmf)4] CTH-8 and [Co4(cpb)(acetato)2(dmf)4] CTH-9 are isostructural and form yav-nets; 2(HNEt3)[Fe2(cpb)] CTH-10 and the two polymorphs of 2(H2NMe2)[Zn2(cpb)]∙1.5dmac, Zn-MOF-888 and CTH-11 show kgd-nets; [Cu2(cpb)(acetato)2(dmf)2]∙2dmf, CTH-12 forms a mixed coordination and hydrogen bonded sql-net, and 2(H2NMe2)[Zn2(cpb)] CTH-13 a similarly mixed yav-net. Surface area values (Brunauer–Emmett–Teller, BET) range from 34 m2g-1 for CTH-12 to 303 m2g-1 for CTH-9 for samples activated at 120 °C in dynamic vacuum. All compounds show normal (ten-fold higher) molar CO2 versus N2 uptake at 298 K, except the 19-fold CO2 uptake for CTH-12 containing Cu(II) dinuclear paddlewheels. We also show how perfect hexagons and triangles can combine to a new 3D topology laf, a model of which gave us the idea of foldable network topologies, as the laf-net can fold into a 2D form while retaining the local geometry around each vertex. Other foldable nets identified are cds, cds-a, ths, sqc163, clh, 4,6T84, and tfc covering the basic polygons and their combinations. The impact of this concept on “breathing” MOFs is discussed. The materials after I2 sorption, both from gas phase and from MeOH solution, into CTH-7 was studied by Time of Flight - Secondary Ion Mass Spectrometry (ToF-SIMS) on dried crystals. I2 was shown to have penetrated the crystals as layers were consecutively peeled off by the ion beam. We suggest ToF-SIMS to be a method for studying sorption depth profiles of MOFs.

A metal-organic framework (MOF) CTH-17 based on lanthanum(III) and the conformationally chiral linker 1,2,3,4,5,6-hexakis(4-carboxyphenyl)benzene, cpb^6-: [La₂(cpb)]·1.5dmf was prepared by the solvothermal method in dimethylformamide (dmf) and characterized by variable-temperature X-ray powder diffraction (VTPXRD), variable-temperature X-ray single-crystal diffraction (SCXRD), and thermogravimetric analysis (TGA). CTH-17 is a rod-MOF with new topology och. It has high-temperature stability with Sohncke space groups P6₁22/P6₅22 at 90 K and P622 at 300 and 500 K, all phases characterized with SCXRD and at 293 K also with three-dimensional (3D) electron diffraction. VTPXRD indicates a third phase appearing after 620 K and stable up to 770 K. Gas sorption isotherms with N₂ indicate a modest surface area of 231 m² g^-1 for CTH-17, roughly in agreement with the crystal structure. Carbon dioxide sorption reveals a gate-opening effect of CTH-17 where the structure opens up when the loading of CO₂ reaches approximately ∼0.45 mmol g^-1 or 1 molecule per unit cell. Based on the SCXRD data, this is interpreted as flexibility based on the concerted movements of the propeller-like hexatopic cpb linkers, the movement intramolecularly transmitted by the π-π stacking of the cpb linkers and helped by the fluidity of the LaO₆ coordination sphere. This was corroborated by density functional theory (DFT) calculations yielding the chiral phase (P622) as the energy minimum and a completely racemic phase (P6/mmm), with symmetric cpb linkers representing a saddle point in a racemization process.

A series of co-crystals of vanillic acid (VA) with caffeine (CAF), theophylline (THP), theobromine (THB), nicotinamide (NAM), isonicotinamide (INM), acridine (ACR) and urea (U) have successfully been prepared. The co-crystals involving the methylated xanthines indicate different host: guest ratios with co-crystals VA·2CAF, 2VA·THP and the co-crystal hydrate VA·THB·2H₂O. The nicotinamide and acridine co-crystals (VA·NAM and VA·ACR) displayed 1 : 1 molar ratios in contrast to the isonicotinamide co-crystal hydrate 2VA·2INM·2H₂O. Co-crystallisation of vanillic acid with urea gave 2VA·2U. The co-crystals and co-crystal hydrates were characterised by single crystal X-ray diffraction and thermal analysis. Grinding and slurry experiments were also performed.