Bao S.-S., Li N.-Z., Taylor J.M. et al. · Chemistry of Materials · 2015 · 8116-8125
Open a family to keep every result attached to its sample, method and conditions.
Paraphrased for this database from the authors’ stated interpretations — never quoted verbatim — and kept separate from reported measurements.
CoCa.nH2O is a promising impedance humidity sensor because conductivity/impedance switches strongly and reversibly with RH, with fast single-crystal response and recovery.
Caveat: Single-crystal device is fastest; pressed powder pellets require much longer equilibration.
main p.7, article p.8122 · Humidity Sensing Properties · Figure 5; SI Figure S22 · Linked to 8 structured results
The CoCa framework retains crystallinity after full dehydration and can rehydrate to CoCa.2H2O or CoCa.4H2O depending on humidity.
Caveat: Full dehydration was assigned from in situ PXRD/TGA and Pawley fitting rather than single-crystal structure.
main p.5, article p.8120 · Thermal Stability · Figure 2b; SI Figure S2 · Linked to 2 structured results
CoCa.nH2O undergoes reversible humidity-dependent single-crystal-to-single-crystal transformation between CoCa.2H2O and CoCa.4H2O at room temperature.
Caveat: CoCa.3H2O is inferred from sorption and not isolated as a pure XRD phase.
main p.1, article p.8116 · Abstract · Linked to 4 structured results
The continuous H-bond network in CoCa.4H2O is interrupted in CoCa.2H2O, giving an approximately five-order decrease in proton conductivity under lower humidity.
Caveat: Conductivity curves are smooth because the RH interval in conductivity measurements was 5%, which may hide sharper hydration transitions.
main p.5, article p.8120 · Proton Conduction of Powdered Sample · Figures 2c and 3 · Linked to 6 structured results
Single-crystal conductivity is highly anisotropic; [010] is the preferred proton-conduction pathway.
Caveat: Only three crystallographic directions were measured.
main p.7, article p.8122 · Single Crystal Proton Conduction · Figure 4 · Linked to 3 structured results
ClO4- anions connect lattice water molecules and phosphonate oxygen atoms into H-bond networks and likely assist proton diffusion; the high activation energies suggest a vehicle mechanism rather than purely Grotthuss conduction.
Caveat: Mechanistic assignment is inferred from crystallographic pathways, H-bond network analysis and activation energies, not direct proton-motion spectroscopy.
main p.7, article p.8122 · Single Crystal Proton Conduction · SI Figure S16 · Linked to 6 structured results
Names and aliases are kept exactly within the paper’s own identity model.
| Material | Composition | Structure context | Source |
|---|---|---|---|
| CoCa.2H2O lower-humidity phase | [CoIII CaII(notpH2)(H2O)2]ClO4.2H2O; C9H28N3P3O17ClCoCaCo(III)-Ca(II) phosphonate framework with two coordinated and two lattice water molecules. · notpH2(4-) phosphonate ligand. | 2D · PristineMonoclinic P21/n phase obtained by humidity lowering; framework layer topology remains comparable to CoCa.4H2O but extended H-bond network is interrupted. | main p.4, article p.8119 · Structural Description · Table 1; Figure 1d |
| CoCa.3H2O intermediate hydration state | [CoIII CaII(notpH2)(H2O)2]ClO4.3H2OCo(III)-Ca(II) phosphonate framework. · notpH2(4-) phosphonate ligand. | 2D · PristineHydrated intermediate inferred from adsorption/desorption uptake; pure phase not isolated for XRD. | main p.5, article p.8120 · Water Adsorption/Desorption Isotherms · Figure 2c |
| CoCa.4H2O hydrated phase | [CoIII CaII(notpH2)(H2O)2]ClO4.4H2O; C9H32N3P3O19ClCoCaCo(III) octahedra and Ca(II) distorted octahedra connected through phosphonate oxygen atoms. · notpH2(4-) phosphonate ligand. | 2D · PristineMonoclinic P21/n 2D waved layer with four lattice water molecules and continuous two-dimensional H-bond network in the a-b plane at high humidity. | main p.3, article p.8118 · Structural Description · Table 1; Figure 1 |
| CoCa-de fully dehydrated framework | [CoIII CaII(notpH2)]ClO4Dehydrated Co(III)-Ca(II) phosphonate framework retaining crystallinity. · notpH2(4-) phosphonate ligand. | 2D · PristineFully dehydrated phase indexed as monoclinic P21/n from PXRD/Pawley fit. | main p.5, article p.8120 · Thermal Stability · Figure 2b; SI Figure S2 |
| CoCa.nH2O layered cobalt-calcium phosphonate | [CoIII CaII(notpH2)(H2O)2]ClO4.nH2OHeterometallic Co(III)-Ca(II) nodes; Co is octahedral CoO3N3 and Ca is distorted octahedral CaO6. · notpH2(4-) derived from notpH6 = 1,4,7-triazacyclononane-1,4,7-triyl-tris(methylenephosphonic acid), C9H18N3(PO3H2)3. | 2D · PristineLayered 2D phosphonate framework with positively charged layers balanced by interlayer ClO4- anions and lattice water; reversible hydration states n = 0, 2, 3, 4 are discussed. | main p.1, article p.8116 · Abstract |
Sample form, processing state and composition status define the context for measurements.
| Sample | Form and role | Processing and geometry | Source |
|---|---|---|---|
| Air-dried CoCa.2H2O crystalsresearch_0802__mat__coca_2h2o | Single Crystal · Target Sample · Pristine Framework | Obtained by drying fresh CoCa.4H2O crystals in air at ca. 30 C and ca. 50% RH for 2 weeks. | main p.3, article p.8118 · Experimental Section - Preparation of CoCa.2H2O |
| Fresh violet sheet-like CoCa.4H2O crystalsresearch_0802__mat__coca_4h2o | Single Crystal · Target Sample · Pristine Framework | Crystallised from aqueous filtrate after pH adjustment and standing at room temperature for 3 days. | main p.3, article p.8118 · Experimental Section - Preparation of CoCa.4H2O |
| Activated/dehydrated CoCa-de powderresearch_0802__mat__coca_de | Powder · Target Sample · Pristine Framework | CoCa.nH2O pretreated at 120 C under vacuum for 2 h before water sorption; in situ PXRD also assigns fully dehydrated material after heating. | main p.5, article p.8120 · Water Adsorption/Desorption Isotherms · Figure 2c |
| Pressed CoCa.nH2O pellet for proton conductivityresearch_0802__mat__coca_nh2o_framework | Pellet · Target Sample · Pristine Framework | Pellet pressed under ca. 0.15 GPa and measured by AC impedance under controlled RH.2.5 mm diameter, 0.58 mm thickness | main p.5, article p.8120 · Proton Conduction of Powdered Sample · Figure 2c inset; SI Figures S5-S7 |
| CoCa.nH2O powder/pellet humidity sensor samplesresearch_0802__mat__coca_nh2o_framework | Pellet · Target Sample · Pristine Framework | Powder pellets or unpressed powder measured at 1 kHz and 0.1 V while cycling RH between 55% and 95%.Gold electrodes for round/square pellets; titanium electrode/glass arrangement for unpressed powder in SI Figure S22. · Round pellet: phi 2.5 mm, 0.60 mm; square pellet: 2.0 x 2.0 x 0.44 mm3; powder layer: 8.0 x 4.0 x 0.4 mm3. | SI p.S17 · Figure S22 caption and diagram · Figure S22 |
| CoCa.nH2O powder for water adsorption/desorptionresearch_0802__mat__coca_nh2o_framework | Powder · Target Sample · Pristine Framework | Humidity-varied powder derived from activated CoCa-de during water adsorption/desorption isotherms. | main p.5, article p.8120 · Water Adsorption/Desorption Isotherms · Figure 2c |
| CoCa.nH2O single crystal measured along [010]research_0802__mat__coca_nh2o_framework | Single Crystal · Target Sample · Pristine Framework | Crystal faces indexed; crystal cut to expose face and contacted with gold wires/gold paste for quasi-four-probe AC impedance.0.70 x 0.29 x 0.08 mm3 for [010] direction measurement | main p.6, article p.8121 · Single Crystal Proton Conduction · Figure 4; SI Figures S8-S11, S17 |
| CoCa.nH2O single crystal measured along [202]research_0802__mat__coca_nh2o_framework | Single Crystal · Target Sample · Pristine Framework | Crystal faces indexed and contacted for AC impedance along [202].0.65 x 0.30 x 0.15 mm3 for [202] direction measurement | main p.6, article p.8121 · Single Crystal Proton Conduction · Figure 4; SI Figures S12-S13, S18 |
| CoCa.nH2O single crystal measured along [20-1]research_0802__mat__coca_nh2o_framework | Single Crystal · Target Sample · Pristine Framework | Crystal faces indexed and contacted for AC impedance along [20-1].0.58 x 0.33 x 0.11 mm3 for [20-1] direction measurement | main p.6, article p.8121 · Single Crystal Proton Conduction · Figure 4; SI Figures S14-S15, S19 |
| CoCa.nH2O single-crystal humidity sensor along [010]research_0802__mat__coca_nh2o_framework | Single Crystal · Target Sample · Pristine Framework | Single crystal measured at 1 kHz and 0.1 V while cycling RH between 55% and 95%.0.60 x 0.30 x 0.10 mm3 | main p.7, article p.8122 · Humidity Sensing Properties · Figure 5 |