The Next Chapter in MOF Pillaring Strategies: Trigonal Heterofunctional Ligands To Access Targeted High-Connected Three Dimensional Nets, Isoreticular Platforms

A new pillaring strategy, based on a ligand-to-axial approach that combines the two previous common techniques, axial-to-axial and ligand-to-ligand, and permits design, access, and construction of higher dimensional MOFs, is introduced and validated. Trigonal heterofunctional ligands, in this case isophthalic acid cores functionalized at the 5-position with N-donor (e.g., pyridyl- or triazolyl-type) moieties, are designed and utilized to pillar pretargeted two-dimensional layers (supermolecular building layers, SBLs). These SBLs, based on edge transitive Kagomé and square lattices, are cross-linked into predicted three-dimensional MOFs with tunable large cavities, resulting in isoreticular platforms

The Next Chapter in MOF Pillaring Strategies: Trigonal Heterofunctional Ligands To Access Targeted High-Connected Three Dimensional Nets, Isoreticular Platforms

A new pillaring strategy, based on a ligand-to-axial approach that combines the two previous common techniques, axial-to-axial and ligand-to-ligand, and permits design, access, and construction of higher dimensional MOFs, is introduced and validated. Trigonal heterofunctional ligands, in this case isophthalic acid cores functionalized at the 5-position with N-donor (e.g., pyridyl- or triazolyl-type) moieties, are designed and utilized to pillar pretargeted two-dimensional layers (supermolecular building layers, SBLs). These SBLs, based on edge transitive Kagomé and square lattices, are cross-linked into predicted three-dimensional MOFs with tunable large cavities, resulting in isoreticular platforms

The Next Chapter in MOF Pillaring Strategies: Trigonal Heterofunctional Ligands To Access Targeted High-Connected Three Dimensional Nets, Isoreticular Platforms

A new pillaring strategy, based on a ligand-to-axial approach that combines the two previous common techniques, axial-to-axial and ligand-to-ligand, and permits design, access, and construction of higher dimensional MOFs, is introduced and validated. Trigonal heterofunctional ligands, in this case isophthalic acid cores functionalized at the 5-position with N-donor (e.g., pyridyl- or triazolyl-type) moieties, are designed and utilized to pillar pretargeted two-dimensional layers (supermolecular building layers, SBLs). These SBLs, based on edge transitive Kagomé and square lattices, are cross-linked into predicted three-dimensional MOFs with tunable large cavities, resulting in isoreticular platforms

The Next Chapter in MOF Pillaring Strategies: Trigonal Heterofunctional Ligands To Access Targeted High-Connected Three Dimensional Nets, Isoreticular Platforms

A new pillaring strategy, based on a ligand-to-axial approach that combines the two previous common techniques, axial-to-axial and ligand-to-ligand, and permits design, access, and construction of higher dimensional MOFs, is introduced and validated. Trigonal heterofunctional ligands, in this case isophthalic acid cores functionalized at the 5-position with N-donor (e.g., pyridyl- or triazolyl-type) moieties, are designed and utilized to pillar pretargeted two-dimensional layers (supermolecular building layers, SBLs). These SBLs, based on edge transitive Kagomé and square lattices, are cross-linked into predicted three-dimensional MOFs with tunable large cavities, resulting in isoreticular platforms

The Next Chapter in MOF Pillaring Strategies: Trigonal Heterofunctional Ligands To Access Targeted High-Connected Three Dimensional Nets, Isoreticular Platforms

A new pillaring strategy, based on a ligand-to-axial approach that combines the two previous common techniques, axial-to-axial and ligand-to-ligand, and permits design, access, and construction of higher dimensional MOFs, is introduced and validated. Trigonal heterofunctional ligands, in this case isophthalic acid cores functionalized at the 5-position with N-donor (e.g., pyridyl- or triazolyl-type) moieties, are designed and utilized to pillar pretargeted two-dimensional layers (supermolecular building layers, SBLs). These SBLs, based on edge transitive Kagomé and square lattices, are cross-linked into predicted three-dimensional MOFs with tunable large cavities, resulting in isoreticular platforms

Bridging Structure, Magnetism, and Disorder in Iron-Intercalated Niobium Diselenide, Fe x NbSe2, below x = 0.25

Transition-metal dichalcogenides (TMDs) intercalated with magnetic ions serve as a promising materials platform for developing next-generation, spin-based electronic technologies. In these materials, one can access a rich magnetic phase space depending on the choice of intercalant, host lattice, and relative stoichiometry. The distribution of these intercalant ions across given crystals, however, is less well defined-particularly away from ideal packing stoichiometries-and a convenient probe to assess potential longer-range ordering of intercalants is lacking. Here, we demonstrate that confocal Raman spectroscopy is a powerful tool for mapping the onset of intercalant superlattice formation in Fe-intercalated NbSe2 (FexNbSe2) for 0.14 ≤ x < 0.25. We use single-crystal X-ray diffraction to confirm the presence of longer-range intercalant superstructure and employ polarization-, temperature-, and magnetic field-dependent Raman measurements to examine both the symmetry of emergent phonon modes in the intercalated material and potential magnetoelastic coupling. Magnetometry measurements further indicate a correlation between the onset of magnetic ordering and the relative degree of intercalant superlattice formation. These results show Raman spectroscopy to be an expedient, local probe for mapping intercalant ordering in this class of magnetic materials

Multispectral fluorescence imaging to assess pH in biological specimens

Simple, quantitative assays to measure pH in tissue could improve the study of complicated biological processes and diseases such as cancer. We evaluated multispectral fluorescence imaging (MSFI) to quantify extracellular pH (pHe) in dye-perfused, surgically-resected tumor specimens with commercially available instrumentation. Utilizing a water-soluble organic dye with pH-dependent fluorescence emission (SNARF-4F), we used standard fluorimetry to quantitatively assess the emission properties of the dye as a function of pH. By conducting these studies within the spectroscopic constraints imposed by the appropriate imaging filter set supplied with the imaging system, we determined that correction of the fluorescence emission of deprotonated dye was necessary for accurate determination of pH due to suboptimal excitation. Subsequently, employing a fluorimetry-derived correction factor (CF), MSFI data sets of aqueous dye solutions and tissuelike phantoms could be spectrally unmixed to accurately quantify equilibrium concentrations of protonated (HA) and deprotonated (A−) dye and thus determine solution pH. Finally, we explored the feasibility of MSFI for high-resolution pHe mapping of human colorectal cancer cell-line xenografts. Data presented suggest that MSFI is suitable for quantitative determination of pHe in ex vivo dye-perfused tissue, potentially enabling measurement of pH across a variety of preclinical models of disease

π Donation and Its Effects on the Excited-State Lifetimes of Luminescent Platinum(II) Terpyridine Complexes in Solution

Introducing electron-donating groups extends the excited-state lifetimes of platinum­(II)–terpyridine complexes in fluid solution. Such systems are of interest for a variety of applications, viz., as DNA-binding agents or as components in luminescence-based devices, especially sensors. The complexes investigated here are of the form [Pt­(4′-X-T)­Y]⁺, where 4′-X-T denotes a 4′-substituted 2,2′:6′,2″-terpyridine ligand and Y denotes the coligand. The π-donating abilities of −X and −Y increase systematically in the orders −NHMe < −NMe₂ < −(pyrrolidin-1-yl) and −CN < −Cl < −CCPh, respectively. The results presented include crystal structures of two new 4′-NHMe-T complexes of platinum, as well as absorption, emission, and excited-state lifetime data for nine complexes. Excited-state lifetimes obtained in deoxygenated dichloromethane vary by a factor of 100, ranging from 24 μs for [Pt­(4′-pyrr-T)­CN]⁺ to 0.24 μs for [Pt­(4′-ma-T)­Cl]⁺, where ma-T denotes 4′-(methylamino)-2,2′:6′,2″-terpyridine and pyrr-T denotes 4′-(pyrrolidin-1-yl)-2,2′:6′,2″-terpyridine. Analysis of experimental and computational results shows that introducing a simple amine group on the terpyridine and/or a π-donating coligand engenders the emitting state with intraligand charge-transfer (ILCT) and/or ligand–ligand charge-transfer (LLCT) character. The excited-state lifetime increases when the change in orbital parentage lowers the emission energy, suppresses quenching via d–d states, and encourages delocalization of the excitation onto the ligand(s). At some point, however, the energy is low enough that direct vibronic coupling to the ground-state surface becomes important, and the lifetime begins to decrease again

π Donation and Its Effects on the Excited-State Lifetimes of Luminescent Platinum(II) Terpyridine Complexes in Solution

Introducing electron-donating groups extends the excited-state lifetimes of platinum­(II)–terpyridine complexes in fluid solution. Such systems are of interest for a variety of applications, viz., as DNA-binding agents or as components in luminescence-based devices, especially sensors. The complexes investigated here are of the form [Pt­(4′-X-T)­Y]⁺, where 4′-X-T denotes a 4′-substituted 2,2′:6′,2″-terpyridine ligand and Y denotes the coligand. The π-donating abilities of −X and −Y increase systematically in the orders −NHMe < −NMe₂ < −(pyrrolidin-1-yl) and −CN < −Cl < −CCPh, respectively. The results presented include crystal structures of two new 4′-NHMe-T complexes of platinum, as well as absorption, emission, and excited-state lifetime data for nine complexes. Excited-state lifetimes obtained in deoxygenated dichloromethane vary by a factor of 100, ranging from 24 μs for [Pt­(4′-pyrr-T)­CN]⁺ to 0.24 μs for [Pt­(4′-ma-T)­Cl]⁺, where ma-T denotes 4′-(methylamino)-2,2′:6′,2″-terpyridine and pyrr-T denotes 4′-(pyrrolidin-1-yl)-2,2′:6′,2″-terpyridine. Analysis of experimental and computational results shows that introducing a simple amine group on the terpyridine and/or a π-donating coligand engenders the emitting state with intraligand charge-transfer (ILCT) and/or ligand–ligand charge-transfer (LLCT) character. The excited-state lifetime increases when the change in orbital parentage lowers the emission energy, suppresses quenching via d–d states, and encourages delocalization of the excitation onto the ligand(s). At some point, however, the energy is low enough that direct vibronic coupling to the ground-state surface becomes important, and the lifetime begins to decrease again