Electrically Conductive Photoluminescent Porphyrin Phosphonate Metal–Organic Frameworks

Abstract

as paddle wheel patterns. [6,7] The ligandbinding modes around such molecular IBUs form large angles, ensuring separation between the organic struts and, in turn, resulting in large void spaces. [11] On the other hand, such separation limits the electrostatic interactions between the organic linkers. Therefore, traditional MOFs lack the required electron hopping and extended conjugation mechanisms between the bridging ligands to support electron mobility. [12][13][14] Although high surface area MOFs are ideal platforms to host electrons for supercapacitor applications, due to the lack of such mechanisms, conventional arylcarboxylate MOFs are generally known to be insulators. In addition to electrically conductive MOFs, photoluminescent MOFs have been the subject of active research due to their applications in sensing and light emitting diodes (LEDs). [15][16][17][18][19] In most cases, the photoluminescence is achieved either by the use of photoluminescent metal ions such as lanthanides, addition of fluorescent dyes to the MOF pores, or ligand exchange. [17,20] On the other hand, the photoluminescence in MOFs originating purely from the organic moieties is extremely rare and, to the best of our knowledge, there are no electrically conductive MOFs with high photoluminescence in the literature.Two-dimensional π-stacked MOFs based on ortho-diimine, ortho-dihydroxy, azolate, and thiolate metal-binding groups Herein, the design and synthesis of a highly photoluminescent and electrically conductive metal-organic framework [Zn{Cu-p-H 6 TPPA}]⋅2 [(CH 3 ) 2 NH](designated as GTUB3), which is constructed using the 5,10,15,20-tetrakis [p-phenylphosphonic acid] porphyrin (p-H 8 TPPA) organic linker, is reported. The bandgap of GTUB3 is measured to be 1.45 and 1.48 eV using diffuse reflectance spectroscopy and photoluminescence (PL) spectroscopy, respectively. The PL decay measurement yields a charge carrier lifetime of 40.6 ns. Impedance and DC measurements yield average electrical conductivities of 0.03 and 4 S m −1 , respectively, making GTUB3 a rare example of an electrically conductive 3D metal-organic framework. Thermogravimetric analysis reveals that the organic components of GTUB3 are stable up to 400 °C. Finally, its specific surface area and pore volume are calculated to be 622 m 2 g −1 and 0.43 cm 3 g −1 , respectively, using grand canonical Monte Carlo. Owing to its porosity and high electrical conductivity, GTUB3 may be used as a low-cost electrode material in next generation of supercapacitors, while its low bandgap and high photoluminescence make it a promising material for optoelectronic applications.

Multifunctionality of luminescent molecular nanomagnets based on lanthanide complexes

“…[103][104][105][106][107][108][109] Both luminescent materials built from Ln(III) complexes and 4f-metal-based SMMs have been independently explored as the source of multifunctionality. The Ln(III) complexes were found to combine luminescent effects with second harmonic generation (SHG), [110][111][112] proton or electronic conductivity, 113,114 and catalytic activity, 115,116 as well as sensitivity to solvent molecules, [117][118][119] various chemicals, [120][121][122] and light. [123][124][125] Non-emissive Ln(III) molecular nanomagnets have also been successfully functionalized, in particular, towards chemical and photo-switching abilities, [126][127][128][129] ferroelectricity, 130 and chirality.…”

Microporous Metal‐Phosphonates with a Novel Orthogonalized Linker and Complementary Guests: Insights for Trivalent Metal Complexes from Divalent Metal Complexes

“…[23][24][25][26][27][28] Similar to the sulfonate functional group, phosphonates exhibit an abundance of coordination modes and additionally, have varying degrees of protonation. [29][30][31] The double edge of the structural pliancy is that metal-phosphonates often pack to form nonporous layered structures with minimal porosity. In addition, coordinating to higher-valent metals with the goal of yielding robust solids, frequently results in rapidly precipitated products that make structural characterization difficult.…”

“…Alternatively, phosphonate linkers have received significant interest due to their ability to strongly bind metal ions resulting in thermally and chemically resistant MOF structures [23–28] . Similar to the sulfonate functional group, phosphonates exhibit an abundance of coordination modes and additionally, have varying degrees of protonation [29–31] . The double edge of the structural pliancy is that metal‐phosphonates often pack to form nonporous layered structures with minimal porosity.…”

Cationic Metal–Organic Frameworks Synthesized from Cyclotetraphosphazene Linkers with Flexible Tentacles

“…Metal–organic framework (MOF) research has gained significant attention recently. − The well-ordered microporous MOF architectures could find many applications in small molecule storage, catalysis, magnetism, drug delivery, food chemistry, supercapacitors, and so forth. − More than 90,000 MOF structures have been deposited into crystal structure databases. , A recent study reported by Fairen-Jimenez and co-workers has shown that only about 8000 of the reported MOFs are microporous. , To date, MOF synthesis is predominantly dependent on carboxylate linkers, which is followed by pyridine- and azolate-functionalized linkers. In addition, the use of sulfonate, phosphonate, orto-diimine, and quinoid metal binding groups have been emerging in MOF synthesis with structurally rigid aromatic cores in liner, Y-shaped, X-shaped geometrical cores. ,− To the best of our knowledge, not all of the geometrical core possibilities in MOF synthesis has been exploited yet.…”