A microporous silicoaluminophosphate with a novel topology type, STA-20, has been prepared via a dual templating method using hexamethylene bisdiazabicyclooctane (diDABCO-C6) and trimethylamine as cotemplates. Its structure has been solved and confirmed using a multitechnique approach that included the use of a hypothetical zeolite database to obtain a candidate starting structure, followed by scanning transmission electron microscopy with annular dark field imaging and Rietveld refinement. STA-20 is a member of the ABC-6 family of zeotype structures. The structure has trigonal symmetry, P-31c, with a = 13.15497(18) Å and c = 30.5833(4) Å in the calcined form. It has a 12-layer stacking sequence of 6-rings (6Rs), AABAABAACAAC(A), which contains single and double 6R units. In addition to d6r, can, and gme cages, STA-20 possesses the longest cage observed in an ordered ABC-6 material, giving a 3D-connected pore system limited by 8R windows. Models for the location of the templates within cages of the framework were obtained by combining elemental analysis, 13C MAS NMR, computer modeling, and Rietveld refinement.

Polymorphs of Zn(2-nIm)2 (compound 1) and Co(2-nIm)2 (compounds 2 and 3) (2-nIm = 2-nitroimidazole) have been prepared by two routes: solvothermal synthesis and recrystallisation of ZIF-65(Zn/Co). Compounds 1 and 2 are isostructural, with a tetrahedrally-connected framework topology related to, but different from, that of tridymite (lonsdaleite). Single crystal X-ray diffraction analysis showed that in compound 1 (Pccn, Z = 8; a = 8.462(8) Å, b = 14.549(15) Å, c = 18.799(18) Å, V = 2314(4) Å3) there is rotational disorder for two of the three crystallographically-distinct linker types, which has been investigated computationally and by solid-state NMR spectroscopy. Detailed adsorption studies on a sample of 1 prepared by recrystallisation show 1.1 mmol g−1 uptake of CO2 at 0.1 bar (25 °C) with high affinity for CO2 over CH4 and N2 (adsorption enthalpies of 39.5, 26.0 and 18.5 kJ mol−1, respectively). A cobalt analogue (compound 2) with improved water stability (but lower porosity) has also been prepared. Changing the conditions of synthesis and recrystallisation gives rise to a cobalt 2-nitroimidazolate (Co(2-nIm)2, compound 3), which has a layered structure (I41/amd, a = 6.025(18) Å, c = 26.95(8) Å, V = 978.3(5) Å3) containing sheets of tetrahedrally-connected Co2+ cations composed of four membered rings, without porosity.

The use of transition metal cations complexed by polyamines as structure directing agents (SDAs) for silicoaluminophosphate (SAPO) zeotypes provides a route, via removal of the organic by calcination, to microporous solids with well-distributed, catalytically-active extra-framework cations and avoids the need for post-synthesis aqueous cation exchange. Iron(II) complexed with tetraethylenepentamine (TEPA) is found to be an effective SDA for SAPO-34, giving as-prepared solids where Fe2+–TEPA complexes reside within the cha cages, as indicated by Mössbauer, optical and X-ray absorption near edge spectroscopies. By contrast, when non-coordinating tetraethylammonium ions are used as the SDAs in Fe-SAPO-34 preparations, iron is included as octahedral Fe3+ within the framework. The complex-containing Fe-SAPO-34(TEPA) materials give a characteristic visible absorption band at 550 nm (and purple colouration) when dried in air that is attributed to oxygen chemisorption. Some other Fe2+ polyamine complexes (diethylenetriamine, triethylenetetramine and pentaethylenehexamine) show similar behaviour. After calcination in flowing oxygen at 550 °C, ‘one-pot’ Fe(TEPA) materials possess Fe3+ cations and a characteristic UV-visible spectrum: they also show appreciable activity in the selective catalytic reduction of NO with NH3.

A retrosynthetic method has been developed to design the synthesis of target zeotypes whose frameworks belong to the ABC-6 structural family and which contain gme cages. This permits the preparation of silicoaluminophosphate versions of AFX (SAPO-56), SFW (STA-18), and GME (STA-19) topology types. The method makes simultaneous use of two organic structure-directing agents (SDAs) to promote the formation of structural features such as cages or channels of the target framework. Computational modeling was used to identify SDAs for gme and other cages or channels in the target structures. The trimethylammonium cation was found to be the most favorable SDA for the gme cage while bisdiazabicyclooctane (DABCO) alkane cations and quaternary ammonium oligomers of DABCO with connecting polymethylene chain lengths of 4–8 methylene units acted as templates for the additional cages or channels, respectively. The incorporation of each of the co-SDAs in the as-prepared materials was confirmed by chemical analysis, 13C MAS NMR, and Rietveld refinement combined with computational modeling. Calcination of the SAPO-56, STA-18, and some of the STA-19 materials gives microporous, fully tetrahedrally coordinated framework solids with AFX, SFW, and GME topologies: other STA-19 samples convert topotactically to SAPO-5. These results show that SAPOs in the ABC-6 family can be prepared via a targeted co-templating approach.

•Extended range of copper–polyamine complex SDAs for SAPO-34.•Cu-N,N′-bis(2-aminoethyl)-1,3-propanediamine complex templates SAPO-18.•Cu2+ cations located in calcined Cu-SAPO-18 and SAPO-34.•Catalytic NH3 SCR of NO compared for ‘one-pot’ Cu-SAPO-18, -SAPO-34 and -SAPO(SAV).Cu2+ cations complexed by linear polyamines have been studied as structure-directing agents (SDAs) for the direct synthesis of copper-containing microporous silicoaluminophosphate (SAPO) materials. The complexing ligands diethylenetriamine (DETA), N-(2-hydroxyethyl)ethylenediamine (HEEDA), triethylenetetramine (TETA), N,N′-bis(2-aminoethyl)-1,3-propanediamine (232), 1,2-bis(3-aminopropylamino)ethane (323), tetraethylenepentamine (TEPA) and pentaethylenehexamine (PEHA) have been investigated. For comparison, syntheses have been performed using the analogous nickel–polyamine complexes. Cu2+ and Ni2+ forms of both SAPO-18 and SAPO-34 materials have been prepared. While most polyamine complexes direct crystallisation to SAPO-34, SAPO-18 has been prepared with Cu2+(232), Ni2+(232) and Ni2+(TETA). The coordination geometry of the included metal complexes was studied by UV–visible and EPR spectroscopy and computer simulation. SAPO-18 is favoured by the smaller square planar complexes or octahedral species (with 2 water molecules) of 232 and TETA. Calcination leaves extra-framework Cu2+ and Ni2+ cations within SAPO-18 and SAPO-34 frameworks. In situ synchrotron IR spectroscopy of Ni-SAPO-18 has shown thermal template degradation occurs via nitrile intermediates. Rietveld structural analysis located extra-framework Cu2+ and Ni2+ cations released by calcination. In SAPO-34, Cu2+ and Ni2+ were located in the 8R window of the cha cage. A second site was found for Ni2+ at the centre of the six-membered rings (6Rs) of the double-six-ring (D6R) sub-units. In SAPO-18 both Cu2+ and Ni2+ cations were located only in the 6Rs of the D6R sub-units. Selected copper SAPO-18 and SAPO-34 samples were tested in the selective catalytic reduction of NO with ammonia (NH3-SCR); both showed high activity.

Adsorption of CO2 and CH4 has been measured on the Na-, K-, and Cs-forms of zeolite Rho (0–9 bar; 283–333 K). Although CH4 is excluded, CO2 is readily taken up, although the uptake at low pressures decreases strongly, in the order Na+ > K+ > Cs+. Structural studies by powder X-ray diffraction (PXRD) suggest that cations in intercage window sites block CH4 adsorption; however, in the presence of CO2, the cations can move enough to permit adsorption (several angstroms). Determination of time-averaged cation positions during CO2 adsorption at 298 K by Rietveld refinement against PXRD data shows that (i) in Na-Rho, there is a small relaxation of Na+ cations within single eight-ring (S8R) sites, (ii) in Cs-Rho, D8R cations move to S8R sites (remaining within windows) and two phases of Cs-Rho (I4̅3m, Im3̅m) are present over a wide pressure range, and (iii) in K-Rho, there is relocation of some K+ cations from window sites to cage sites and two phases coexist, each with I4̅3m symmetry, over the pressure range of 0–1 bar. The final cation distributions at high PCO2 are similar for Na-, K-, and Cs-Rho, and adsorption in each case is only possible by “trapdoor”-type cation gating. Complementary studies on K-chabazite (Si/Al = 3) also show changes in time-averaged cation location during CO2 adsorption.

The use of copper polyamine complexes as structure directing agents for microporous solids offers a direct route to the inclusion of Cu2+ complex cations in their pores: upon calcination, this gives active catalysts for the selective catalytic reduction of NO with NH3. In situ synchrotron IR absorption spectroscopy on crystals of dimensions 25–35 μm has been used to monitor the dehydration of the Cu2+-cyclam complex that acts as a cotemplate for the silicoaluminophosphate SAPO STA-7 and, at higher temperatures (400 °C), the calcination that gives the active catalyst Cu,H-SAPO STA-7. Polarized synchrotron IR microspectroscopy reveals strong alignment of N–H bonds of the Cu2+ cyclam in the larger cages of as-prepared STA-7, and complementary X-ray diffraction, ESR, UV–visible spectroscopy, and computer simulation indicate that the hydrated complex acts as cotemplate during crystallization: dehydration leads to removal of its coordinated water by 200 °C.

The porous metal organic frameworks scandium trimesate MIL-100(Sc), scandium terephthalates MIL-101(Sc), MIL-88B(Sc) and MIL-68(Sc), scandium 4,4′-biphenyl-dicarboxylate MIL-88D(Sc) and the scandium 3,3′,5,5-azobenzene-tetracarboxylate socMOF(Sc) have been compared as Lewis acid catalysts against Sc3+-exchanged zeolite Beta, MIL-100(Cr), MIL-101(Cr), MIL-100(Fe) and the divalent MOFs HKUST-1(Cu), CPO-27(Ni) and STA-12(Ni), each of which can be prepared with coordinatively unsaturated metal sites. The performance of these MOFs has been investigated in several Lewis acid-catalysed reactions that are of importance in organic synthesis but have rarely been studied using MOF catalysts. These reactions were (i) the intermolecular carbonyl ene reaction of nucleophilic alkenes and electron-poor aldehydes, (ii) a Friedel–Crafts type Michael addition between electron-rich heterocycles and electron-deficient alkenes and (iii) ketimine and aldimine formation. In each of these, MIL-100(Sc) is both active and selective and significantly outperforms the other catalysts. Filtration and recycle tests indicate that catalysis over MIL-100(Sc) is heterogeneous. The study of Michael addition reactions carried out over scandium-bearing MOFs with different window sizes on indole-based substrates of varying molecular dimensions indicates that most of the catalysis that involves molecules small enough to enter the pores occurs within the internal pore space. These results indicate MIL-100(Sc) is an exceptional Lewis acidic MOF catalyst, and suggest that MIL-100(Sc) and new derivatives of it could find application as recyclable solid catalysts in synthetic chemistry.

Nickel cations have been introduced into framework sites of the magnesium dioxiterephthalate MOF, CPO-27(Mg), via a procedure involving post-synthetic treatment with an aqueous solution of Ni2+ cations and a weak acid. The final solids have Ni concentrations up to 70 mol% of the total cation content. Selected area EDX analysis, synchrotron X-ray powder diffraction and XPS surface analysis indicate that Ni2+ is distributed throughout the crystals with highest concentration at the external surface. A mechanism involving both crystallisation and predominant isomorphous cation replacement is proposed. The modified solids have much enhanced adsorption capacities following simple thermal evacuation under vacuum than unmodified CPO-27(Mg), particularly for N2 at 77 K, for which uptakes of 17 mmol g−1 are achieved. This is attributed to surface modification that makes the surface more stable to heating under evacuation.

A series of univalent cation forms of zeolite Rho (M9.8Al9.8Si38.2O96, M = H, Li, Na, K, NH4, Cs) and ultrastabilized zeolite Rho (US-Rho) have been prepared. Their CO2 adsorption behavior has been measured at 298 K and up to 1 bar and related to the structures of the dehydrated forms determined by Rietveld refinement and, for H-Rho and US-Rho, by solid state NMR. Additionally, CO2 adsorption properties of the H-form of the silicoalumino-phosphate with the RHO topology and univalent cation forms of the zeolite ZK-5 were measured for comparison. The highest uptakes at 0.1 bar, 298 K for both Rho and ZK-5 were obtained on the Li-forms (Li-Rho, 3.4 mmol g–1; Li-ZK-5, 4.7 mmol g–1). H- and US-Rho had relatively low uptakes under these conditions: extra-framework Al species do not interact strongly with CO2. Forms of zeolite Rho in which cations occupy window sites between α-cages show hysteresis in their CO2 isotherms, the magnitude of which (Na+,NH4+ < K+ < Cs+) correlates with the tendency for cations to occupy double eight-membered ring sites rather than single eight-membered ring sites. Hysteresis is not observed for zeolites where cations do not occupy the intercage windows. In situ synchrotron X-ray diffraction of the CO2 adsorption on Na-Rho at 298 K identifies the adsorption sites. The framework structure of Na-Rho “breathes” as CO2 is adsorbed and desorbed and its desorption kinetics from Na-Rho at 308 K have been quantified by the Zero Length Column chromatographic technique. Na-Rho shows much higher CO2/C2H6 selectivity than Na-ZK-5, as determined by single component adsorption, indicating that whereas CO2 can diffuse readily through windows containing Na+ cations, ethane cannot.

A novel form of mixed-linker ZIF with the RHO topology is one of four zinc-imidazolate frameworks prepared with purine and 2-nitroimidazole. In this structure the linkers order to give a large pore solid with a high pore volume and an unusual symmetry and linker orientation. It possesses extra-framework zinc imidazolate units decorating the internal surface which can be removed to give high porosity.

The crystal chemistry of divalent metal N,N′-piperazinebis(methylenephosphonates) of the STA-12 family, (M2(H2O)2(O3PCH2NC4H8NCH2PO3)·xH2O, M = Mg, Mn, Fe, Co, Ni) is compared. The different metal analogues are isostructural in the hydrated forms, possessing R3¯ symmetry, but their reversible dehydration behaviour and resultant porosity are strongly dependent on the metal cation. Whereas the Co and Ni forms change symmetry to triclinic upon dehydration, giving permanent porosity to N2 of 0.14 cm3 g−1 and 0.27 cm3 g−1, respectively, the Mn and Fe forms remain rhombohedral but exhibit a strong decrease in unit cell volume (e.g. 23% for STA-12(Mn)). Structure determination of dehydrated STA-12(Mn) indicates a topotactic transformation with a change in coordination of the phosphonate O atoms. Negligible permanent porosity is observed in either dehydrated STA-12(Mn) or (Fe), suggesting the presence of non-crystallographic pore blocking. Dehydration of STA-12(Mg) results in loss of some long range order, preventing structural determination of the fully dehydrated form, but does give appreciable permanent porosity for N2 of 0.20 cm3 g−1. Infrared spectroscopy (and for STA-12(Mg) solid-state NMR spectroscopy) have been used to follow the changes upon dehydration. Applications of the most porous and stable STA-12 structure, the Ni form, have also been investigated. CO2 adsorption selectivity over CH4 and CO has been measured via analysis of breakthrough curves, and a Porous Layer Open Tubular (PLOT) gas chromatographic column has been prepared and used to separate a mixture of low molecular weight alkanes.Graphical abstractHighlights► Metal phosphonates STA-12(M), M = Mg, Mn, Fe, Co, and Ni synthesised hydrothermally. ► The different metal forms of STA-12 show strongly divergent dehydration behaviour. ► Dehydrated STA-12 (Mg, Co, and Ni) are permanently porous. ► STA-12 shows good selectivity for CO2 adsorption over CH4 and CO. ► A PLOT capillary GC column with STA-12(Ni) separates low boiling point alkanes.

Crystalline microporous cobalt and nickel bisphosphonates with a hexagonal array of one-dimensional channels 1.8 nm in diameter have been prepared hydrothermally and provide the first example of the use of isoreticular chemistry in the synthesis of phosphonate metal−organic frameworks. The materials contain both physisorbed and coordinating water molecules in the as-prepared form, but these can be removed to give permanent extra-large microporosity, with pore volumes of up to 0.68 cm3 g−1, and coordinatively unsaturated sites, with concentrations up to 4.25 mmol g−1.

The crystal structure of the small pore scandium terephthalate Sc2(O2CC6H4CO2)3 (hereafter Sc2BDC3, BDC = 1,4-benzenedicarboxylate) has been investigated as a function of temperature and of functionalization, and its performance as an adsorbent for CO2 has been examined. The structure of Sc2BDC3 has been followed in vacuo over the temperature range 140 to 523 K by high resolution synchrotron X-ray powder diffraction, revealing a phase change at 225 K from monoclinic C2/c (low temperature) to Fddd (high temperature). The orthorhombic form shows negative thermal expansivity of 2.4 × 10–5 K–1: Rietveld analysis shows that this results largely from a decrease in the c axis, which is caused by carboxylate group rotation. 2H wide-line and MAS NMR of deuterated Sc2BDC3 indicates reorientation of phenyl groups via π flips at temperatures above 298 K. The same framework solid has also been prepared using monofunctionalized terephthalate linkers containing -NH2 and -NO2 groups. The structure of Sc2(NH2-BDC)3 has been determined by Rietveld analysis of synchrotron powder diffraction at 100 and 298 K and found to be orthorhombic at both temperatures, whereas the structure of Sc2(NO2-BDC)3 has been determined by single crystal diffraction at 298 K and Rietveld analysis of synchrotron powder diffraction at 100, 298, 373, and 473 K and is found to be monoclinic at all temperatures. Partial ordering of functional groups is observed in each structure. CO2 adsorption at 196 and 273 K indicates that whereas Sc2BDC3 has the largest capacity, Sc2(NH2-BDC)3 shows the highest uptake at low partial pressure because of strong -NH2···CO2 interactions. Remarkably, Sc2(NO2-BDC)3 adsorbs 2.6 mmol CO2 g–1 at 196 K (P/P0 = 0.5), suggesting that the -NO2 groups are able to rotate to allow CO2 molecules to diffuse along the narrow channels.

Conditions for the synthesis of each of the scandium terephthalate frameworks Sc2L3, MIL-53(Sc) (Sc(OH)L) and MIL-88(Sc) (Sc3O(H2O)2(OH)L3) (L = 1.4-benzenedicarboxylate (BDC)) have been established. In addition, the MOFs MIL-100(Sc) (Sc3O(H2O)2(OH)L′2, L′ = 1,3,5-benzenetricarboxylate (BTC)) and socMOF (Sc3O(H2O)3,(NO3−)L″1.5, L″ = 3,3′,5,5′-azobenzenetetracarboxylate (ABTC)), have been synthesised for the first time with Sc. These materials have been characterised by powder and single crystal X-ray diffraction, 1H, 13C and 45Sc MAS NMR, and gas adsorption. MIL-53(Sc) is a highly flexible breathing framework that adopts many different forms, depending on the amount and type of adsorbate included. The structures of the as-prepared solvent-containing form, MIL-53(Sc)-DMF (DMF = dimethylformamide) and of the desolvated, hydrated form, MIL-53(Sc)-H2O, have been determined. The former structure possesses one kind of partially open channel, whereas the latter includes two kinds of channel, closed and slightly open. The hydrated structure’s configuration has not previously been observed for MIL-53 materials. 45Sc MAS NMR is a sensitive probe for the Sc environment: distinctive lineshapes are observed for isolated ScO6 octahedra, corner-sharing chains of ScO4(OH)2 octahedra and Sc3O(O2C-)6(OH, H2O)3 trimers of octahedra. N2 adsorption at 77 K indicates that the flexible frameworks MIL-88(Sc) and MIL-53(Sc) show no porosity in their desolvated, closed forms, whilst the rigid frameworks Sc2BDC3 (0.26 cm3 g−1), MIL-100(Sc) (0.72 cm3 g−1) and Sc-ABTC (0.57 cm3 g−1) have so far been prepared with appreciable permanent porosity. For CO2 adsorption on desolvated solids, remarkable behaviour is shown by the flexible MIL-53(Sc), which opens in two stages to a maximum capacity of >13 mmol g−1, while the rigid frameworks show uptakes at 196 K (at p/po = 0.40) of 5.5 mmol g−1 (Sc2BDC3), 21.3 mmol g−1 (MIL-100(Sc)) and 13.1 mmol g−1 (Sc-ABTC).Graphical abstractResearch highlights► Synthesis of scandium analogues of the microporous carboxylate-based MOFs MIL-53, MIL-88, MIL-100, MIL-101 and socMOF. ► Crystallographic analysis of MIL-53(Sc) structure in novel as-prepared and hydrated forms. ► Scandium-45 MAS NMR characterisation of Sc-MOFs with different types of metal-containing sub-units. ► Observation of a new type of 2-step adsorption isotherm of CO2 on a MIL-53 type MOF.

Copper cyclam (cyclam = 1,4,8,11-tetraazacyclotetradecane) and tetraethylammonium (TEA+) act as co-templates for the hydrothermal crystallisation of the silicoaluminophosphate SAPO STA-7, as determined by UV–visible, ESR and solid-state MAS NMR spectroscopies, powder and single crystal X-ray diffraction and chemical analysis. Calcination of the as-prepared solid in flowing oxygen removes all organics to leave Cu(II),H-SAPO STA-7 (hereafter Cu-SAPO STA-7) in which the presence of bridging hydroxyl groups is confirmed by IR and the presence of multiple environments for Cu2+ is shown by IR using NO as a probe molecule. Rietveld analysis of synchrotron X-ray powder diffraction data collected over the temperature range 293–673 K locates Cu2+ cations distributed over four sites: above six membered rings (6MRs) and in the three different 8MR windows of the STA-7 structure. Cu-SAPO STA-7 is a very good catalyst for the selective catalytic reduction of NO with NH3, in the presence or absence of water vapour, so that this approach represents an efficient and effective route to copper-containing SAPO catalysts that obviates the need for an aqueous Cu2+ ion exchange step during preparation.Graphical abstractCopper cyclam and tetraethylammonium act as co-templates for SAPO STA-7. Calcination of the as-prepared solid leaves Cu2+-containing SAPO STA-7- a direct route to a very good catalyst for the selective catalytic reduction of NO with NH3.Highlights► The SAPO STA-7 framework is co-templated by tetraethylammonium cations and copper cyclam complexes. ► Calcination results in liberation of Cu2+ from the complex and its re-distribution into extra framework sites. ► Variable temperature synchrotron X-ray powder diffraction of calcined, Cu,H-SAPO STA-7 locates Cu2+ in four different sites: 6MR sites and three different 8MR sites. ► Cu,H-SAPO STA-7 is a very good catalyst for the SCR of NO in the presence and absence of H2O.

The influence of the chemical composition and of the storage and activation protocol on the diffusion of methanol into strongly chemically zoned crystals of the silicoaluminophosphate zeotype STA-7 has been investigated by interference microscopy. Analysis of the evolution of transient intracrystalline concentration profiles reveals that just-calcined SAPO STA-7 crystals with lower Si content (Si/(Si + P) = 0.18) exhibit higher surface permeability and bulk diffusivity than those with higher Si content (S/(Si + P) = 0.37). Remarkably, crystals with the higher Si content which were stored in the calcined form crack during activation along planes of weakness already present in the as-prepared crystals, creating fresh surfaces through regions of lower Si that are much more easily penetrated by the adsorbing methanol than are the original surfaces.

The novel aluminophosphate STA-15 (St Andrews microporous solid-15) is prepared by hydrothermal synthesis in the presence of tetrapropylammonium hydroxide (TPAOH), which acts as a structure directing agent. The crystallization is accelerated by the addition of low concentrations of tetraphenylphosphonium or other bulky organic cations, and the purity is improved by the addition of silica to the gel, but these additives are not included in the final crystalline product. The structure of STA-15 was solved by a combination of synchrotron X-ray powder diffraction and modeling. The as-prepared form of STA-15 (Iba2, a = 14.7953(1) Å, b = 27.3634(3) Å, c = 8.34464(6) Å at 100 K) has unit cell composition Al32P32O128(OH)1.8TPA1.8·3H2O. It has a system of one dimensional channels, limited by strongly elliptical 12-membered rings (12 tetrahedral cations and 12 oxygen atoms, 8.7 × 5.7 Å ) in which the TPA+ cations reside. The charge-balancing hydroxide ions are coordinated to framework Al, as shown by 27Al and 31P MAS NMR. STA-15 is stable to removal of the organic and hydroxyl species upon calcination in oxygen, leaving a microporous solid with a pore volume of 0.11 cm3 g-1 and showing uptakes of n-hexane and toluene (at 297 K, p/po = 0.10) of 0.48 and 0.69 mmol g−1, respectively.

Crystallisation of yttrium and other trivalent metal cations of similar radius with racemic N,N′-2-methylpiperazinebis(methylene phosphonic acid) gives a small pore bisphosphonate metal–organic framework solid displaying coordinative and hydrogen bonding and permanent porosity.

Molecular modeling has been used to assist in the design of a new structure directing agent (SDA) for the synthesis of the AlPO4 form of STA-2, bis-diazabicyclooctane-butane (BDAB). This is incorporated as a divalent cation within the large cages of STA-2, as determined via a combination of solid-state 13C and 15N MAS NMR, supported by 14N and 1H-15N HMQC solution NMR and density functional calculations. As-prepared AlPO4 STA-2 containing cationic SDA molecules achieves neutrality by the inclusion of hydroxide ions bridging between 5-fold coordinated framework Al atoms. Synchrotron X-ray powder diffraction data of the dehydrated as-prepared form indicates triclinic symmetry (Al12P12O48(OH)2·BDAB, P1, a = 12.3821(2) Å, b = 12.3795(2) Å, c = 12.3797(3) Å, α = 63.3585(8)°, β = 63.4830(7)°, γ = 63.4218(7)°) with the distortion from rhombohedral R3̅ symmetry resulting from the partial order of hydroxide ions in bridging Al−OH−Al sites within cancrinite cages. Upon calcination in oxygen, the organic SDA is removed, leaving AlPO4 STA-2 with a pore volume of 0.22 cm3 g−1 (R3̅, Al36P36O144, a = 12.9270(2) Å, c = 30.7976(4) Å). Dehydrated calcined AlPO4 STA-2 has two crystallographically distinct P and Al sites: 31P MAS NMR resolves the two distinct P sites, and although 27Al MAS NMR only partially resolves the two Al sites, they are separated by MQMAS. Furthermore, 2D 27Al → 31P MQ-J-HETCOR correlation spectroscopy confirms that each framework Al is linked to the two different P sites via Al−O−P connections in a 3:1 ratio (and vice versa for P linked to different Al). The 27Al and 31P resonances are assigned to the crystallographic Al and P sites by calculation of the NMR parameters using the CASTEP DFT program for an energy-minimized AlPO4(SAT) framework.

Details of the synthesis of the small-pore silicoaluminophosphate (SAPO) molecular sieves STA-7 (SAV) and STA-14 (KFI) prepared via a co-templating approach are described. STA-7 includes Si in the framework with Si/(Si+Al+P) ratios varying from 0.04 to 0.17, whereas STA-14 crystallizes from gels with a narrower compositional range (Si/(Si+Al+P) = 0.2−0.3). The main route to Si incorporation is by substitution for P, but in the presence of fluoride, aluminosilicate regions are formed in STA-7. 27Al 3Q MAS NMR studies enable resolution of tetrahedral Al in Al(OP)4 and Al(OP3,OSi) environments in both as-prepared and calcined materials. For STA-7 with low Si content the presence of five- and six-fold Al coordinated with water molecules or fluoride or hydroxide ions has also been confirmed. Upon calcination, all Al adopts tetrahedral coordination. High pressure CO2, CO, and CH4 adsorption at 100 °C indicates that the proton forms of the SAPO D6R zeotypes present effective polarities intermediate between cationic zeolites and pure silica chabazite. The methanol-to-olefin (MTO) performance of the SAPOs H-SAPO-34, H-STA-7, and H-STA-14 was found to depend on both crystallite size and cage connectivity and topology. H-STA-7 with a crystal size of 2−3 μm has MTO stability comparable to that observed for H-SAPO-34, whereas the same materials with larger crystal sizes (≥10 μm) deactivate rapidly. Ex situ GC-MS analyses of the SAPO catalysts after MTO reaction demonstrate that the uniformity in cage shape and size in cage-based, small-pore molecular sieves is a critical factor governing the type of the accumulated aromatic hydrocarbons and, hence, their MTO activity and deactivation behavior.

A ‘co-templating’ strategy supported by molecular modelling has been used to prepare, for the first time, silicoaluminophosphates with the SAV and KFI framework topologies, each of which has a three-dimensionally connected pore system with high specific volume.

The first large pore (free diameter > 7 Å) metal phosphonates have been prepared as divalent metal N,N′-piperazinebis(methylenephosphonate)s that possess pores greater than ca. 10 Å in free diameter, are stable up to 400 °C and offer a route to chiral adsorbents and catalysts.

A scandium terephthalate with isolated ScO6 octahedra and fully-linked carboxylate groups is prepared hydrothermally and possesses a novel hybrid framework structure with high thermal stability and a pore volume for N2 adsorption of 0.26 cm3 g−1 at 77 K.

Variable temperature wideline 2H NMR investigations of the mobility of aromatic rings in the framework of desolvated samples of the metal organic framework compound MOF-5 (Zn4O(O2CC6H4CO2)3) and the closely related solid MOCP-L have been performed. The aromatic rings in MOF-5 are stationary at temperatures lower than room temperature but perform 180° (π) flips at higher temperatures until all framework aromatic groups execute this motion at 373 K. The aromatic groups in MOCP-L demonstrate a higher degree of mobility with some motion even below 170 K. 2H NMR of perdeuterobenzene adsorbed onto MOF-5 at a loading of two molecules per Zn4O13 inorganic unit shows that upon cooling below 140 K the motion of benzene changes from isotropic reorientation to rotation about its six-fold axis. Computational simulation suggests that benzene occupies a site close to the Zn4O13 unit at low temperatures.

The effect of the co-condensation of 3-mercaptopropyltriethoxysilane (MPTES) in the preparation of mesoporous silicas has been examined for levels of MPTES of 0–10 mol% (based on silicon) in reported syntheses using the block co-polymers P123 and F127. In syntheses using P123, SBA-15 (p6mm) forms with 0–5 mol% MPTES whereas addition of 7 mol% of the silane results in highly ordered Ia3¯d silica. Using F127, synthesis in the absence of MPTES gives the reported cubic Fm3m FDU-12 structure, based on the cubic close packing of surfactant micelles, whereas addition of MPTES results in the introduction of a high concentration of stacking defects in the close packing sequences and changes in particle morphology. At 5 mol% MPTES, tapered hexagonal prismatic particles with nano-domains of the hexagonally close packed structure (space group P63/mmc) are obtained. The accessible thiol contents in the members of these two series of solids have been determined using Ellman’s reagent (5,5′-dithiobis-(2-nitrobenzoic acid)): values of 50–70% of the thiols incorporated in the solid have been measured as being accessible to this reactant.

Four scandium phosphate-based structures have been prepared hydrothermally in the presence of the primary diamines ethylenediamine and diaminobutane and the primary amine cyclohexylamine and characterised by single crystal and powder X-ray diffraction, 31P and 45Sc solid-state MAS NMR and chemical analysis. Charge balancing protons in the structures are located using bond valence sum calculations and postulated hydrogen bonding networks. Compound 1, [(H3NC2H4NH3)3][Sc3(OH)2(PO4)2(HPO4)3(H2PO4)], P1¯, a=5.4334(6)a=5.4334(6), b=8.5731(9)b=8.5731(9), c=16.3022(18)Å, α=79.732(4)α=79.732(4), β=83.544(4)β=83.544(4), γ=80.891(5)°γ=80.891(5)°, Z=2Z=2, is built up of scandium phosphate ribbons, based on trimers of ScO6 octahedra linked by OH groups. These trimers are joined through phosphate groups bound through three oxygens, and are decorated by phosphate groups linked by a single oxygen atom. The ribbons are arranged parallel to the a-axis and linked one to another by fully protonated ethylenediammonium ions. Compounds 2, [(H3NC4H8NH3)3][(Sc(OH2))6Sc2(HPO4)12(PO4)2], P3¯, a=13.8724(3)a=13.8724(3), c=9.4351(11)Å, Z=1Z=1, and 3, [(H3NC4H8NH3)2(H3O)][Sc5F4(HPO4)8], C2/mC2/m, a=12.8538(4)a=12.8538(4), b=14.9106(4)b=14.9106(4), c=10.1906(3)Å, β=101.17(9)°β=101.17(9)°, Z=2Z=2, were prepared using diaminobutane as the organic template in the absence and presence, respectively, of fluoride ions in the gel. Compound 2 has a pillared layered structure, in which ScO6 octahedra are linked by three vertices of hydrogenphosphate groups into sheets and the sheets pillared by ScO6 octahedra to give a three-dimensionally connected framework isostructural with a previously reported iron(III) hydrogenphosphate. The protonated diaminobutane molecules occupy cavities between the layers. Compound 3 has a layered structure in which isolated ScO6 octahedra and tetrameric arrangements of ScO4F2 octahedra, the latter linked in squares through fluoride ions, are connected by phosphate tetrahedra that share two or three oxygens with scandium atoms. In this structure, the protonated diaminobutane molecules connect the layers, the -NH3+ groups fitting into recesses in the layers. Compound 4, [(C6H11NH3)][ScF(HPO4)(H2PO4)], PbcaPbca, a=7.650(3)a=7.650(3), b=12.867(5)b=12.867(5), c=26.339(11)Å, Z=8Z=8, the first scandium phosphate to be prepared with a monoamine, is also a layered solid. In this case, the layers contain single chains of ScO4F2 octahedra which share fluoride ions in trans positions. Phosphate tetrahedra bridge across scandiums via two of their four oxygens, both within the same chain and also to neighbouring chains to make up the layer. The protonated amine groups of the cyclohexylamine molecules achieve close contact with phosphates of the layer, while the cyclohexyl moieties, which are in the chair configuration, project into the interlayer space.Four novel scandium hydrogenphosphates and fluorophosphates with chain, layered and framework structures have been prepared hydrothermally in the presence of the primary amine cyclohexylamine and the diamines ethylenediamine and diaminobutane.

[Ni(diethylenetriamine)2]2+, (Ni(deta)2), acts as a structure directing agent for aluminophosphates and metalloaluminophosphates with the CHA and AFI framework topologies. In the presence of ammonium fluoride, triclinic Ni(deta)2-UT-6; P , a=9.289(1) Å, b=9.095(1) Å, c=9.356(1) Å, α=88.35(1)°, β=78.91(1)°, γ=89.21(1)°, with the CHA topology and orthorhombic Ni(deta)2-AlPO(F)-5; Ccc2, a=13.8603(5) Å, b=23.1285(5) Å, c=8.5420(4) Å with the AFI topology are prepared, the latter being favoured by higher water contents in the synthesis gel. Upon heating in nitrogen or oxygen at temperatures of 500 °C and above, Ni(deta)2-UT-6 is transformed reconstructively to an aluminophosphate with the AFI topology whereas heating at lower temperatures followed by heating in oxygen at 600 °C removes the organic and gives a solid with the CHA topology. Calcination of all samples prepared in the absence of fluoride leaves the original frameworks intact. Ni K-edge X-ray spectroscopy of Ni(deta)2-UT-6 calcined in oxygen at 600 °C reveals the formation of nanoparticulate NiO.

The mesoporous solid SBA-2, prepared at room temperature in alkaline pH using the gemini surfactant [CH3(CH2)15N(CH3)2(CH2)3N(CH3)3]2+ can adopt hollow sphere (ca. 100 μm diameter), flat plate (50 μm across) and small sphere (1–2 μm diameter) morphologies. Plates appear to be formed directly by fracturing of the hollow spheres. The nanostructure of these materials is consistent with templating around close packed micelles. X-Ray diffraction and high resolution imaging show that the structure of these preparations ranges from mainly hexagonal to mainly cubic close packing.

The synthesis of mesoporous silicas in the presence of the dicationic gemini surfactant [CH3(CH2)15N(CH3)2(CH2)3N(CH3)3]Br2 (C16-3-1) has been investigated at low temperatures (−4 °C) under basic and acidic conditions. Under basic conditions, the SBA-2 phase (based on a close-packed arrangement of micelles and exhibiting frequent stacking faults) is observed, with hollow sphere morphology. Under strongly acidic conditions, the phase SBA-1 (Pmn) and the SBA-2 family of phases (based on the close packing of micelles) are observed, depending on the surfactant and silicate content of the original gel. Conditions under which the pure hexagonally close-packed end member of the family (P63/mmc) is formed have been identified. SBA-1 and the pure hexagonally close-packed end member are prepared with well-defined morphologies. The adsorption of nitrogen and the hydrocarbons cyclopentane and mesitylene reveal that SBA-2 prepared in basic media has a cage structure where the cages are linked through small (<4 Å) micropores, whereas the silicas prepared in acidic media have larger pores after calcination. SBA-1 and a poorly ordered SBA-2, prepared using C16-3-1 under acidic conditions, are able to adsorb mesitylene (diameter ca. 8 Å), whereas the hexagonal end member of the SBA-2 series prepared under acidic conditions is able to adsorb cyclopentane (diameter ca. 5 Å) but not mesitylene.

Nickel complexed with the azamacrocycle 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane (tmtact) acts to direct the crystallisation of metalloaluminophosphate (MAPO, M = Mg, Mn, Co, Zn) and silicoaluminophosphate (SAPO) gels to an orthorhombic variant of the STA-6 material (structure code SAS) and to mixtures of this phase with STA-7 (structure code SAV). Compositional analysis, diffuse reflectance UV-visible spectroscopy, magnetic susceptibility and solid state NMR of pure STA-6 samples show that the nickel remains complexed within the macrocycle after crystallisation, adopting square planar geometry. The positive charge on the divalent complex is balanced by the negative charge imparted to the framework by the aliovalent substitution of divalent cations for aluminium or the incorporation of silicon for phosphorus. Crystallographic analysis of a single crystal of the Ni(tmtact)–CoAPO form of STA-7 (P4/n, a = 18.684(1) Å, c = 9.408(1) Å) is able to locate the complex, disordered about the 4-fold axis, within supercages in the structure. The inorganic framework of the Ni(tmtact)2+-templated STA-6 solids remains intact as the organics are removed by calcination, and the STA-6 becomes tetragonal. The paramagnetic Ni2+ cations are left within the pore structure. Reduction of the calcined sample in hydrogen at temperatures of 473–523 K gives Ni(I), as shown by ESR spectroscopy, g = 2.09.

The mesoporous silica SBA-15, functionalised with propylthiol groups during synthesis and rendered porous (mean pore diameter 51 Å) by extraction of surfactant template molecules, shows strong and size selective adsorption of proteins, selectively excluding those with molecular weights of ca. 40000 u and above. A model for the adsorption process is proposed, in which reversible physisorption is followed by irreversible chemisorption. Adsorption of proteins on an unfunctionalised SBA-15 from which the template has been removed by calcination, (mean pore diameter 56 Å) shows shape selective and reversible adsorption of proteins with molecular weights of ca. 43000 u and below.

The synthesis of the three-dimensional hexagonal mesoporous silica SBA-2 has been studied as a function of pH, temperature and type of gemini surfactant template. SBA-2 is formed from reaction mixtures with a pH between 10 and 12, with the best ordered samples being obtained in the pH range 11–12. In the most highly ordered samples domains may extend to microns in dimension. Increasing pH within this range gives SBA-2 with unit cells decreasing from 380(10) to 220(7) nm3. Upon calcination the unit cell volumes decrease to between 253(8) and 136(5) nm3, and the average pore size decreases by ≈20%. Incorporation of aluminium in tetrahedral sites at Si/Al ratios of >11 also gives SBA-2, but reduces the degree of order. The adsorption characteristics of these aluminosilicates are very similar to pure silica SBA-2 prepared with the same surfactant. Upon calcination the aluminium adopts tetrahedral, 5-fold and octahedral environments, and imparts solid acidity of sufficient strength to catalyse the isomerisation of butene with high selectivities to butenes and conversions to isobutene of up to 26%. The catalysts deactivate only slowly on stream as the pore volume is filled with carbonaceous residue.

A novel layered lead titanate with the approximate composition PbTiO2(CO3)0.3 (NO3)0.35(OH) has been synthesized hydrothermally under acidic conditions. The structure has been solved and refined from X-ray and neutron powder diffraction data in the space group P -3 1 m, with cell dimensions a = 5.1787(5) Å and c = 8.5222(7) Å. The titanate layers possess a gibbsite-like structure: lead cations and oxyanions such as carbonate and nitrate are included between the layers. Upon heating the solid loses water, carbon dioxide and nitrogen dioxide and converts via a poorly crystalline intermediate phase to the perovskite PbTiO3. The conversion is complete by 550°C; continued heating results in an increase in crystallinity.

A ‘co-templating’ strategy supported by molecular modelling has been used to prepare, for the first time, silicoaluminophosphates with the SAV and KFI framework topologies, each of which has a three-dimensionally connected pore system with high specific volume.

A novel form of mixed-linker ZIF with the RHO topology is one of four zinc-imidazolate frameworks prepared with purine and 2-nitroimidazole. In this structure the linkers order to give a large pore solid with a high pore volume and an unusual symmetry and linker orientation. It possesses extra-framework zinc imidazolate units decorating the internal surface which can be removed to give high porosity.

Crystallisation of yttrium and other trivalent metal cations of similar radius with racemic N,N′-2-methylpiperazinebis(methylene phosphonic acid) gives a small pore bisphosphonate metal–organic framework solid displaying coordinative and hydrogen bonding and permanent porosity.

The porous metal organic frameworks scandium trimesate MIL-100(Sc), scandium terephthalates MIL-101(Sc), MIL-88B(Sc) and MIL-68(Sc), scandium 4,4′-biphenyl-dicarboxylate MIL-88D(Sc) and the scandium 3,3′,5,5-azobenzene-tetracarboxylate socMOF(Sc) have been compared as Lewis acid catalysts against Sc3+-exchanged zeolite Beta, MIL-100(Cr), MIL-101(Cr), MIL-100(Fe) and the divalent MOFs HKUST-1(Cu), CPO-27(Ni) and STA-12(Ni), each of which can be prepared with coordinatively unsaturated metal sites. The performance of these MOFs has been investigated in several Lewis acid-catalysed reactions that are of importance in organic synthesis but have rarely been studied using MOF catalysts. These reactions were (i) the intermolecular carbonyl ene reaction of nucleophilic alkenes and electron-poor aldehydes, (ii) a Friedel–Crafts type Michael addition between electron-rich heterocycles and electron-deficient alkenes and (iii) ketimine and aldimine formation. In each of these, MIL-100(Sc) is both active and selective and significantly outperforms the other catalysts. Filtration and recycle tests indicate that catalysis over MIL-100(Sc) is heterogeneous. The study of Michael addition reactions carried out over scandium-bearing MOFs with different window sizes on indole-based substrates of varying molecular dimensions indicates that most of the catalysis that involves molecules small enough to enter the pores occurs within the internal pore space. These results indicate MIL-100(Sc) is an exceptional Lewis acidic MOF catalyst, and suggest that MIL-100(Sc) and new derivatives of it could find application as recyclable solid catalysts in synthetic chemistry.