Mixed-ligand lanthanide complexes supported by ditopic bis(imino-methyl)-phenol/calix[4]arene macrocycles: synthesis, structures, and luminescence properties of [Ln2(L2)(MeOH)2] (Ln = La, Eu, Tb, Yb)

Aggregation-Induced Modulation of Ground and Excited State Photophysics of 5-(tert-Butyl)-2-Hydroxy-1,3-Isophthalaldehyde (5-tBHI)

5-(tert-Butyl)-2-hydroxy-1,3-isophthalaldehyde (5-tBHI) is a photochromic material susceptible to either excited state proton transfer or excited state intramolecular proton transfer, depending upon the solvent. However, it has also been found to aggregate in the presence of sodium dodecyl sulfate. In this current study, based on the steady-state and time-resolved spectroscopy, supported by crystallography, quantum chemical density functional theory calculation, and molecular dynamics (MD) simulation, we report on the aggregation of this potential single benzene-based emitter (SBBE) in neat solvents as well as solid phase to modulate its photophysics. It has been found that 5-tBHI forms mixed aggregates of different orders, owing to the presence of both enolic and tautomeric forms, to yield tunable emission, although the emission intensity is quenched. These findings suggest that the intramolecular hydrogen bonding of 5-tBHI not only limits intermolecular interactions but also promotes nonradiative deactivation pathways. Hence, designing and structural engineering, with a focus to suppressing intramolecular hydrogen bonding as well as increasing through space conjugation by replacing the aldehydic moieties with bulky aliphatic or aromatic ketonic groups, can be a plausible approach to yielding improved probes with tunable emission and higher fluorescence quantum yields.

Dehydroabietylamine-decorated imino-phenols: supramolecular gelation and gel phase selective detection of Fe3+, Cu2+ and Hg2+ ions under different experimental conditions

Dehydroabietylamine-linked Schiff bases 1–3 have been synthesized, characterized and employed in metal ion sensing in a sol–gel medium. The compounds have a propensity for gel formation from aqueous organic solvents.

Triazolated calix[4]semitubes: assembling strategies towards long multicalixarene architectures

Cone and 1,3-alternate calix[4]arenes bearing pairs of 2-azidoethyl or propargyl groups, and 1,3-alternate calix[4]arenes having four 2-azidoethyl, four propargyl groups or pairs of 2-azidoethyl and silylated propargyl groups were explored...

Tetra-substituted p-tert-butylcalix[4]arene with phosphoryl and salicylamide functional groups: synthesis, complexation and selective extraction of f-element cations

A new series of lanthanide ( 1-5 ) and uranyl ( 6 ) complexes with a tetra-substituted bifunctional calixarene ligand H 2 L is described. The coordination environment for the Ln 3+ and UO 2 2+ ions is provided by phosphoryl and salicylamide functional groups appended to the lower rim of the p-tert -butylcalix[4]arene scaffold. Ligand interactions with lanthanide cations (light: La 3+ , Pr 3+ ; intermediate: Eu 3+ and Gd 3+ ; and heavy: Yb 3+ ), as well as the uranyl cation (UO 2 2+ ) is examined in the solution and solid state, respectively with spectrophotometric titration and single crystal X-ray diffractometry. The ligand is fully deprotonated in the complexation of trivalent lanthanide ions forming di-cationic complexes 2:2 M: L , [Ln 2 ( L ) 2 (H 2 O)] 2+ ( 1 - 5 ), in solution, whereas uranyl formed a 1:1 M: L complex [UO 2 ( L )(MeOH)] ∞ ( 6 ) that demonstrated very limited solubility in 12 organic solvents. Solvent extraction behaviour is examined for cation selectivity and extraction efficiency. H 2 L was found to be an effective extracting agent for UO 2 2+ over La 3+ and Yb 3+ cations. The separation factors at pH 6.0 are: [[EQUATION]] = 121.0 and [[EQUATION]] = 70.0.

Theoretical Modeling (Sparkle RM1 and PM7) and Crystal Structures of the Luminescent Dinuclear Sm(III) and Eu(III) Complexes of 6,6,7,7,8,8,8- Heptafluoro-2,2-dimethyl-3,5-octanedione and 2,3-Bis(2-pyridyl)pyrazine: Determination of Individual Spectroscopic Parameters for Two Unique Eu3+ Sites

Heteroleptic homo dinuclear complexes [Sm(fod)₃(μ-bpp)Sm(fod)₃] and [Eu(fod)₃(μ-bpp)Eu(fod)₃] and their diamagnetic analogue [Lu(fod)₃(μ-bpp)Lu(fod)₃] (fod is the anion of 6,6,7,7,8,8,8- heptafluoro-2,2-dimethyl-3,5-octanedione (Hfod) and bpp is 2,3-bis(2-pyridyl)pyrazine) are synthesized and thoroughly characterized. The lanthanum gave a 1:1 adduct of La(fod)₃ and bpp with the molecular formula of [La(fod)₃bpp]. The ¹H NMR and ¹H-¹H COSY spectra of the complexes were used to assign the proton resonances. In the case of paramagnetic Sm³⁺ and Eu³⁺ complexes, the methine (of the fod moiety) and the bpp resonances are shifted in the opposite direction and the paramagnetic shifts are dipolar in nature, which decrease with increasing distance of the proton from the metal ion. The single-crystal X-ray analyses reveal that the complexes (Sm³⁺ and Eu³⁺) are dinuclear and crystallize in the triclinic P1 space group. Each metal in a given complex is eight coordinate by coordinating with six oxygen atoms of three fod moieties and two nitrogen atoms of the bpp. Of the two metal centers, in a given complex, one has a distorted square antiprism arrangement and the other acquires a distorted dodecahedron geometry. The Sparkle RM1 and PM7 optimized structures of the complexes are also presented and compared with the crystal structure. Theoretically observed bond distances are in excellent agreement with the experimental values, and the RMS deviations for the optimized structures are 2.878, 2.217, 2.564, and 2.675 Å. The photophysical properties of Sm³⁺ and Eu³⁺ complexes are investigated in different solvents, solid, and PMMA-doped thin hybrid films. The spectroscopic parameters (the Judd-Ofelt intensity parameters, radiative parameters, and intrinsic quantum yield) of each Eu³⁺ sites are calculated using the overlap polyhedra method. The theoretically obtained parameters are close to the experimental results. The lifetime of the excited state is 38.74 μs for Sm³⁺ and 713.62 μs for the Eu³⁺ complex in the solid state.