Three-Dimensional Metal-Catecholate Frameworks and Their Ultrahigh Proton Conductivity

Abstract

A series of three-dimensional (3D) extended metal catecholates (M-CATs) was synthesized by combining the appropriate metal salt and the hexatopic catecholate linker, H6THO (THO(6-) = triphenylene-2,3,6,7,10,11-hexakis(olate)) to give Fe(THO)·Fe(SO4) (DMA)3, Fe-CAT-5, Ti(THO)·(DMA)2, Ti-CAT-5, and V(THO)·(DMA)2, V-CAT-5 (where DMA = dimethylammonium). Their structures are based on the srs topology and are either a 2-fold interpenetrated (Fe-CAT-5 and Ti-CAT-5) or noninterpenetrated (V-CAT-5) porous anionic framework. These examples are among the first catecholate-based 3D frameworks. The single crystal X-ray diffraction structure of the Fe-CAT-5 shows bound sulfate ligands with DMA guests residing in the pores as counterions, and thus ideally suited for proton conductivity. Accordingly, Fe-CAT-5 exhibits ultrahigh proton conductivity (5.0 × 10(-2) S cm(-1)) at 98% relative humidity (RH) and 25 °C. The coexistence of sulfate and DMA ions within the pores play an important role in proton conductivity as also evidenced by the lower conductivity values found for Ti-CAT-5 (8.2 × 10(-4) S cm(-1) at 98% RH and 25 °C), whose structure only contained DMA guests.

Selective CO2 Capture and High Proton Conductivity of a Functional Star‐of‐David Catenane Metal–Organic Framework

“…The reproducibility of this result was good up to five temperature cycles. Activation energy is low and is also comparable with other highly proton‐conductive MOFs . It is also further evidence for the hydrophilic nature of the hexagrammic channels in compound 1 ; hydrazine groups and adsorbed H 2 O molecules effectively form a dense hydrogen‐bonding network, allowing short proton‐transport pathways.…”

“…Similar measurements on a pellet of 1.30 mm in diameter and 2.5 mm in thickness demonstrated similar result (Figure a, and Figure S29, Supporting Information). This clearly indicates that water adsorbed in the pores of compound 1 plays an important role in the proton conduction pathway and the observed conductivity at 98% RH is among the highest values for proton‐conducting MOFs . The high proton conductivity along with its durability against low concentration H 2 O 2 aqueous solution implies potential application of compound 1 for proton exchange fuel cell .…”

Metal–Organic Frameworks and Other Crystalline Materials for Ultrahigh Superprotonic Conductivities of 10−2 S cm−1 or Higher

“…Yaghi et al. synthesized a new type of 3D framework named M‐CATs (metal cathacolates) that are based on a hexacatecholate linker . Bearing Me 2 NH 2 + counter cations as guests in the pores and bound sulfate anions in Fe‐CAT‐5, it was determined to have a proton‐conduction value of 5×10 −2 S cm −1 , whereas Ti‐CAT‐5, which contained only Me 2 NH 2 + cations, had a conduction value of 8.2×10 −4 S cm −1 at 98 % RH and 25 °C.…”

“…Yaghi et al synthesized an ew type of 3D framework named M-CATs (metalc athacolates) that are based on ah exacatecholate linker. [22] Bearing Me 2 NH 2 + counter cations as guestsi nt he pores and bound sulfatea nionsi nF e-CAT-5, it was determined to have ap roton-conduction value of 5 10 À2 Scm À1 ,w hereas Ti-CAT-5, which contained only Me 2 NH 2 + cations, had ac onductionv alue of 8.2 10 À4 Scm À1 at 98 %R Ha nd 25 8C. Ti-CAT-5a dsorbs more water molecules per formula unit than does Fe-CAT-5, which suggestst hat water content in the framework is not the sole factor governing the conductivity.I nstead, the guests and counterions within the pores could play important roles in the overall conductivity as well.…”

Designed Cluster Assembly of Multidimensional Titanium Coordination Polymers: Syntheses, Crystal Structure and Properties

“…However,t he documented Ti CPs or the so-called Ti metal-organic frameworks (TiM OFs) thus far are still relatively rare. [21][22][23][24][25][26][27] In fact, due to the high reactivity of the commonly employed Ti precursors, the controllable synthesiso f multidimensional Ti CPs is still challenging. Therefore, to develop as imple, universal synthetic strategy of Ti CPs is particularly necessary.…”