The idea is examined that steric crowding in ligands can lead to diminution of the chelation enhanced fluorescence (CHEF) effect complexes small Zn(II) ion as compared larger Cd(II) ion. Steric less severe for and smaller leads Zn-N bond length distortion, which allows some quenching by photoinduced electron transfer (PET) mechanism. Some metal complexing properties ligand tris(2-quinolylmethyl)amine (TQA) are presented support more sterically efficient ligands, M-N distortion with ion, will...

Abstract Carbon capture and storage is an important strategy for stabilizing the increasing concentration of atmospheric CO 2 global temperature. A possible approach toward reversing this trend decreasing to remove directly from air (direct capture). Herein we report a simple aqueous guanidine sorbent that captures ambient binds it as crystalline carbonate salt by guanidinium hydrogen bonding. The resulting solid has very low solubility ( K sp =1.0(4)×10 −8 ), which facilitates its...

LiCl is a classic "hard" ion salt that present in lithium-rich brines and key component end-of-life materials (that is, used lithium-ion batteries). Its isolation purification from like salts recognized challenge with potential strategic economic implications. Herein, we describe two ditopic calix[4]pyrrole-based ion-pair receptors (2 3), are capable of selectively capturing LiCl. Under solid-liquid extraction conditions, using 2 as the extractant, could be separated NaCl/KCl mixture...

Fundamental understanding of the selective recognition and separation f-block metal ions by chelating agents is crucial importance for advancing sustainable energy systems. Current investigations in this area are mostly focused on study inner-sphere interactions between donor groups ligands, while effects selectivity resulting from molecular outer-sphere region have been largely overlooked. Herein, we explore fundamental origins solvating extractant N,N,N',N'-tetraoctyl diglycolamide (TODGA)...

The subtle energetic differences underpinning adjacent lanthanide discrimination are explored with diglycolamide ligands. Our approach converges liquid-liquid extraction experiments solution-phase X-ray absorption spectroscopy (XAS) and density functional theory (DFT) simulations, spanning the series. homoleptic [(DGA)3Ln]3+ complex was confirmed in organic extractive solution by XAS, this modeled using DFT. An interplay between steric strain coordination energies apparently gives rise to a...

We report a bench-scale direct air capture (DAC) process comprising CO2 absorption with aqueous amino acid salts (i.e., potassium glycinate, sarcosinate), followed by room-temperature regeneration of the acids reaction solid meta-benzene-bis(iminoguanidine) (m-BBIG), resulting in crystallization hydrated m-BBIG carbonate salt, (m-BBIGH2)(CO3)(H2O)n (n = 3–4). The is subsequently released mild heating (60–120 °C) crystals, which regenerates quantitatively. This low-temperature...

Cage-type calix[4]pyrroles 2 and 3 bearing two additional pyrrole groups on the strap have been synthesized. Compared with parent calix[4]pyrrole (1), they were found to exhibit remarkably enhanced affinities for anions, including sulfate anion (TBA(+) salts), in organic media (CD2Cl2). This increase is ascribed participation of bipyrrole units binding. Receptors extract hydrophilic (as methyltrialkyl(C(8-10))ammonium (A336(+)) salt) from aqueous into a chloroform phase significantly...

A large porphyrin analogue, cyclo[6]pyridine[6]pyrrole, containing no meso bridging atoms, has been synthesized through Suzuki coupling. In its neutral form, this macrocycle exists as a mixture of two figure-eight conformers that undergo fast exchange in less polar solvents. Upon protonation, the dynamic twist can be transformed into species adopt ruffled planar structure or shape depending on extent protonation and counteranions. Conversion to bisboron difluoride complex via deprotonation...

An effective approach to sulfate separation from aqueous solutions is based on the crystallization of extended [SO4(H2O)5(2-)]n sulfate-water clusters with a bis(guanidinium) ligand. The ligand was generated in situ by hydrazone condensation water, thereby bypassing need for elaborate syntheses, tedious purifications, and organic solvents. Crystallization represents an alternative now established strategies that involve encapsulation "naked" anion.

The selectivity of the rigid ligand PDA (1,10-phenanthroline-2,9-dicarboxylic acid) for some M(III) (M = metal) ions is presented. structure [Fe(PDA(H)1/2)(H2O)3] (ClO4)2·3H2O·1/2H5O2 (1) reported: triclinic, P1̅̅, a 7.9022(16) Å, b 12.389(3) c 13.031(3) α 82.55(3)°, β 88.41(3)°, γ 78.27(3)°, V 1238.6(4) Å3, Z 2, R 0.0489. coordination geometry around Fe(III) close to regular pentagonal bipyramid, with Fe−N lengths averaging 2.20 which normal 1,10-phenanthroline type coordinated...

Selective crystallization of sulfate with a simple bis-guanidinium ligand, self-assembled in situ from terephthalaldehyde and aminoguanidinium chloride, was employed as an effective way to separate the highly hydrophilic anion aqueous solutions. The resulting bis-iminoguanidinium salt has exceptionally low solubility (Ksp =2.4×10-10 ), comparable that BaSO4 . Single-crystal X-ray diffraction analysis showed anions are sequestered [(SO4 )2 (H2 O)4 ]4- clusters within crystals....

Abstract Direct air capture (DAC) technologies that extract carbon dioxide from the atmosphere via chemical processes have potential to restore atmospheric CO 2 concentration an optimal level. This study elucidates structure‐property relationships in DAC by crystallization of bis(iminoguanidine) (BIG) carbonate salts. Their crystal structures are analyzed X‐ray and neutron diffraction accurately measure key structural parameters including molecular conformations, hydrogen bonding,...

Negative emission technologies, including direct air capture (DAC) of carbon dioxide, are now considered essential for mitigating climate change, but existing DAC processes tend to have excessively high energy requirements, mostly associated with sorbent regeneration. Here, we demonstrate a promising approach that combines atmospheric CO2 absorption by an aqueous oligopeptide (e.g., glycylglycine) bicarbonate crystallization simple guanidine compound glyoxal-bis-iminoguanidine). In this...

Bis-triazine phenanthrolines have shown great promise for f-block metal separations, attributable to their highly preorganized structure, nitrogen donors, and more enhanced covalent bonding with actinides over lanthanides. However, limited solubility in traditional solvents remains a technological bottleneck. Herein we report our recent work using simple 2,9-bis(triazine)-1,10-phenanthroline (Me-BTPhen) dissolved an ionic liquid (IL), demonstrating the efficacy of IL extraction systems...

1,10-Phenanthroline-2,9-dicarboxamide complexants decorated with alkyl chains and imidazolium cations have been studied for extraction of trivalent f-ions into ionic liquids.

Metal ion complexing properties of the ligand 2,9-bis(hydroxymethyl)-1,10-phenanthroline (PDALC) are reported. For PDALC, rigid 1,10-phenanthroline backbone leads to high levels preorganization and enhanced selectivity for larger metal ions with an ionic radius about 1.0 Å that can fit well into cleft ligand. Structures PDALC complexes two ions, Ca(II) Pb(II), [Ca(PDALC)2](ClO4)2 (1) is triclinic, Pı̅, a = 7.646(3), b 13.927(4), c 14.859(5) (Å), α 72.976(6), β 89.731(6), μ 78.895(6)°, V...

Some metal ion complexing properties of DPP (2,9-Di(pyrid-2-yl)-1,10-phenanthroline) are reported with a variety Ln(III) (Lanthanide(III)) ions and alkali earth ions, as well the uranyl(VI) cation. The intense π–π* transitions in absorption spectra aqueous solutions 10–5 M were monitored function pH concentration to determine formation constants alkali-earth (Ln = lanthanide) ions. It was found that log K1(DPP) for has peak at Sm(III) plot K1 versus 1/r+ (r+ ionic radius 8-coordination). For...

We report a novel di(imino)guanidinium anion extractant with unparalleled selectivity for sulfate in liquid-liquid separation system. In addition to 4.4 order-of-magnitude enhancement affinity compared standard benchmark, our alkylated receptor is economically synthesized and features good compatibility application-relevant aliphatic solvents. Small-angle X-ray scattering results reveal the formation of reverse-micelles, which together significant organic-phase water content challenge...

Selenium (Se) has become an environmental contaminant of aquatic ecosystems as a result human activities, particularly mining, fossil fuel combustion, and agricultural activities. By leveraging the high sulfate concentrations relative to Se oxyanions (i.e., SeO n2-, n = 3, 4) present in some wastewaters, we have developed efficient approach Se-oxyanion removal by cocrystallization with bisiminoguanidinium (BIG) ligands that form crystalline sulfate/selenate solid solutions. The...

The metal ion selectivity for M(III) (M = metal) ions exhibited by the highly preorganized ligand PDALC is investigated (PDALC 2,9-bis(hydroxymethyl)-1,10-phenanthroline). structures are reported of [Bi(PDALC)(H(2)O)(2)(ClO(4))(3)] x H(2)O (1), monoclinic, P2(1)/c, a 12.8140(17), b 19.242(3), c 9.2917(12) A, beta 91.763(2) degrees, V 2289.9(5) A(3), Z 4, R 0.0428; [Th(PDALC)(NO(3))(4)] 3 (2), P2(1)/n, 7.876(3), 22.827(9), 12.324(5) 94.651(6) 2208.4(15) 0.0669; [Cd(PDALC)(2)](ClO(4))(2) (3)),...

Binding strengths of salicylaldoxime–UO₂²⁺ complexes were quantified using UV/Vis spectroscopy and DFT.