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We report a synthesis of a series of molecular compounds and coordination polymers of Zn2+, Mn2+ Cd2+, Eu3+, and Tb3+ with 4-allyl-2,3,5,6-tetrafluorobenzoic acid (4-Afb) anions and 1,10-phenanthroline with compositions [Zn(H2O)(phen)(4-Afb)2] (1), [Mn(H2O)(phen)(4-Afb)2]n·nH2O (2), [Cd(H2O)(phen)(4-Afb)2]n (3), [Cd(phen)(4-Afb)2]n (4), [Ln2(phen)2(4-Afb)6] (Ln = Eu 5Eu; Tb 5Tb). It is shown that the obtained cadmium coordination polymers have various compositions and structures, depending on crystallization conditions. The prepared compounds are characterized by single-crystal XRD, powder XRD, IR spectroscopy, and CHN analysis. Noncovalent interactions are analyzed using the Hirshfeld surface analysis. It is determined that the crystal packings is mainly stabilized by π⋯π, C–H⋯F, and C–F⋯π interactions. The photoluminescent properties of the 5Eu and 5Tb complexes are studied. It is shown that the structure-forming effects of non-covalent "arene–perfluoroarene" interactions can be possibly used for preorganizing reactive functional groups in the crystal. [ABSTRACT FROM AUTHOR]

A study was carried out on the effect of a heavy chlorine atom introduced into the aromatic fragment of a 1,3-diketone ligand in Eu3+ coordination compounds on the spectral and luminescent properties of complex compounds. The data obtained from the absorption, optical excitation, fluorescence, and phosphorescence spectra as well as from the kinetics of the luminescence intensity permit estimation of the efficiency of energy transfer processes within the compounds studied. Introduction of a heavy chlorine atom was found to raise the energy of the first excited singlet state from 24,500 to 26,000 cm–1 but not affect the energy of the triplet level of the ligand. Furthermore, introduction of a chlorine atom leads to a decrease in the nonradiative relaxation constant (from 1290 to 840 s–1) and thereby triples the luminescence quantum yield from 23 to 64%. Hence, a new approach for the rational construction of useful coordination compounds of Eu3+ ions with 1,3-diketone ligands has been developed consisting of the substitution of a hydrogen atom by a heavy chlorine atom in the aromatic fragment of the ligand. [ABSTRACT FROM AUTHOR]

The reaction of 4,4,5,5,6,6,6-heptafluoro-1-(1-methyl-1H-pyrazol-4-yl)hexane-1,3-dione (HPyrC3F7) with freshly precipitated hydrated europium(ɪɪɪ) and samarium(ɪɪɪ) hydroxides in EtOH afforded crystalline complexes of the composition [Ln(PyrC3F7)3(EtOH)2], the features of their formation depending on the stoichiometric ligand/metal ratios were studied. The structure and composition of the complexes were characterized by physicochemical methods, including single-crystal X-ray diffraction. The luminescent properties of these compounds in the crystalline state and in solutions were studied in detail. Possible ways of transferring electronic excitation in the complex [Eu(PyrC3F7)3(EtOH)2] were considered. [ABSTRACT FROM AUTHOR]

Four new complexes [Ln(pfaa)3(H2O)2] n (Ln = Eu (1), Tb (2)) and [Ln2Cd2(pfaa)10 (phen)2(EtOH)2]·2MeCN (Ln = Eu (3), Tb (4), phen = 1,10-phenanthroline) based on pentaphorphenylacetic acid (Hpfaa) have been prepared and completely investigated. The structures of compounds 1 and 3 were studied by single crystal X-ray diffraction analysis: the isostructural complexes 1 and 2 represent 1D coordination polymer, while the isostructural complexes 3 and 4 are molecular compounds. Complexes 1–4 show strong lanthanide-centred luminescence, since the introduction of phenanthroline leads to a significant increase in the observed lifetime (τ obs) and photoluminescent quantum yield. New complexes of Eu3+ and Tb3+ with pentafluorophenylacetic acid have been studied. During synthesis under hydrothermal conditions, polymer structures are formed, while the introduction of phenanthroline and Cd2+ makes it possible to obtain molecular complexes. A change in the structure leads to significant changes in the luminescent properties. [ABSTRACT FROM AUTHOR]

The reaction of Cd(NO3)2 · 4H2O and Eu(NO3)3 · 6H2O or Tb(NO3)3 · 6H2O with potassium 3,5-di-tert-butylbenzoate (Kbzo) and N-donor ligands (1,10-phenanthroline (phen), 2,4-lutidine (2,4-lut), 3,4-lutidine (3,4-lut), phenanthridine (phtd), 2,3-cyclododecenopyridine (cdpy), acridine (acr)) afforded heterometallic LnCd2 complexes: [EuCd2(bzo)7(EtOH)2(phen)] (2), [LnCd2(bzo)7(2,4-lut)4] (Ln = Eu (3), Tb (4)), [EuCd2(bzo)7(H2O)2(2,4-lut)2] · MeCN (5), [EuCd2(NO3)(bzo)6(EtOH)2(2,4-lut)2] (6), [EuCd2(bzo)7(H2O)(EtOH)(3,4-lut)2] · 5EtOH (7), 3[EuCd2(bzo)7(H2O)2(phtd)2] · 4phtd (8), [EuCd2(bzo)7(EtOH)3(cdpy)] (9), 2[EuCd2-(bzo)2(EtOH)4] · acr (10). The structures of complexes 2, 3, and 5–10 were determined by single-crystal X-ray diffraction. The isostructurality of complexes 3 and 4 was confirmed by powder X-ray diffraction. The structure of the trinuclear {Ln2Cd} metal core is stable and independent of the type of peripheral ligands coordinated to cadmium atoms. Photoluminescent properties of compounds 3 and 4 were studied. [ABSTRACT FROM AUTHOR]

Features of nonlinear refraction formation in colloidal solutions containing Ag2S quantum dots passivated with thioglycolic acid (Ag2S/TGA QDs) with a concentration of 0.1% and an average size of 2.0 nm are considered. Nonthermal self-focusing caused by the "band filling" effect under exciton excitation was detected by the Z-scanning method for 10-ns pulses of a YAG:Nd laser at a wavelength of 532 nm for Ag2S/TGA QDs having an exciton absorption maximum at 590 nm. [ABSTRACT FROM AUTHOR]

The condensation reaction of isomeric N-substituted (1 H-pyrazol-4-yl)ethanones with the ethyl esters of pyrazole carboxylic acids and fluoroacetic acids has been studied using NaH as the base. Under optimized conditions, it proved to be a convenient and preparative method for the synthesis of N-substituted (1 H-pyrazolyl)propane-1,3-diones and (1 H-pyrazolyl)-4-polyfluorobutane-1,3-diones. [ABSTRACT FROM AUTHOR]

A reaction of Eu(NO)·6HO with the novel heterocyclic ligand 1,3-bis(1,3-dimethyl-1 H-pyrazol-4-yl)propane-1,3-dione and 1,10-phenanthroline in the presence of NaOH gave the complex Eu(phen)L·5CHCl. The crystal structure of the complex was determined by single-crystal X-ray diffraction. The coordination polyhedron {EuON} is a tetragonal antiprism. The complex shows bright orange-red luminescence in both the solid state and solution. [ABSTRACT FROM AUTHOR]

Four new complexes [Ln(pfaa)3(H2O)2] n (Ln = Eu (1), Tb (2)) and [Ln2Cd2(pfaa)10 (phen)2(EtOH)2]·2MeCN (Ln = Eu (3), Tb (4), phen = 1,10-phenanthroline) based on pentaphorphenylacetic acid (Hpfaa) have been prepared and completely investigated. The structures of compounds 1 and 3 were studied by single crystal X-ray diffraction analysis: the isostructural complexes 1 and 2 represent 1D coordination polymer, while the isostructural complexes 3 and 4 are molecular compounds. Complexes 1–4 show strong lanthanide-centred luminescence, since the introduction of phenanthroline leads to a significant increase in the observed lifetime (τ obs) and photoluminescent quantum yield. New complexes of Eu3+ and Tb3+ with pentafluorophenylacetic acid have been studied. During synthesis under hydrothermal conditions, polymer structures are formed, while the introduction of phenanthroline and Cd2+ makes it possible to obtain molecular complexes. A change in the structure leads to significant changes in the luminescent properties. [ABSTRACT FROM AUTHOR]

Six new complexes of the ligand HQ cy (-4-(cyclohexanecarbonyl)-5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one) and Ln 3+ ions with emission in the near-infrared (Nd 3+ ) or visible and near-infrared (Sm 3+ , Pr 3+ ) spectral regions were synthesized and characterized using various methods, including single crystal X-ray diffraction. The study demonstrated that both tris complexes [LnQ cy 3 (H 2 O)(EtOH)] and tetrakis-acids [H 3 O][LnQ cy 4 ] can be synthesized by varying the synthetic conditions. The photochemical properties of the complexes were investigated experimentally and theoretically using various molecular spectroscopy techniques and Judd-Ofelt theory. The objective was to quantitatively and qualitatively disclose the influence of complex stoichiometry on its luminescence properties. The study showed that the addition of an extra ligand molecule (in the tetrakis species) increased molar extinction by up to 2 times, affected the shape of photoluminescence spectra, especially of the Pr 3+ complex, and increased the quantum yield of the Sm 3+ complex by up to 2 times. The results obtained from this study provide insights into the luminescent properties of lanthanide coordination compounds, which are crucial for the design and development of novel photonic materials with tailored photophysical properties.

Complexes emitting in the blue spectral region are attractive materials for developing white-colored light sources. Here, we report the luminescence properties of novel coordination compounds based on the trivalent group 3, 13 metals, and the 1-phenyl-3-methyl-4-cyclohexylcarbonyl-pyrazol-5-onate (Q CH ) ligand. [M(Q CH ) 3 ] (M = Al, Ga, and In), [M(Q CH ) 3 (H 2 O)] (M = Sc, Gd, and Lu), [Lu(Q CH ) 3 (DMSO)], and [La(Q CH ) 3 (H 2 O)(EtOH)] complexes were synthesized and structurally characterized by a single-crystal X-ray diffraction study. It has been found that the luminescence quantum yields of the ligand increase by one order of magnitude upon metal coordination. A significant correspondence between the energies of the ligand's excited states and the luminescence quantum yields to the metal ion's atomic numbers was found using molecular spectroscopy techniques. The replacement of the central ion with the heavier one leads to a monotonic increase in singlet state energy, while the energy of the triplet state is similar for all the complexes. Time-resolved measurements allowed us to estimate the intersystem crossing (ISC) rate constants. It was shown that replacing the Al 3+ ion with the heavier diamagnetic Ga 3+ and In 3+ ions decreased the ISC rate, while the replacement with the paramagnetic Gd 3+ ion increased the ISC rate, which resulted in a remarkably bright and room-temperature phosphorescence of [Gd(Q CH ) 3 (H 2 O)].

In this study, two novel Pr 3+ complexes with different 1,3-diketonate ligands were synthesized and investigated. To study the effect of the ancillary ligand on the energy transfer mechanisms in the complexes, a phenanthroline ligand was introduced. To take into account the influence of the ligand environment composed of different ligands on the energy transfer and relaxation processes, we compared the synthesized compounds with a similar complex containing the phenanthroline ligand. The spectroscopic studies in the visible and near-infrared spectral regions were supplemented with DFT and TD-DFT calculations. We found two ligand-to-ligand charge transfer (LLCT) states, with one state corresponding to energy transfer between 1,3-diketones and the other - to energy transfer from the 1,3-diketone to the phenanthroline motif. It was demonstrated that optical excitation via the latter channel leads to a fourfold increase in the luminescence quantum yield as compared with excitation via the π-π ∗ transitions in 1,3-diketones. Moreover, both LLCT states provide sensitization of the Pr 3+ luminescence involving the 3 P 0 and 3 P 1 levels., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

A novel, to the best of our knowledge, approach to the design of the single-photon sources emitting in the spectral regions of 1060 and 1337 nm was developed. A unique hybrid structure based on colloidal CdSe/CdS/ZnS nanocrystals and neodymium(III) 1,3-diketonate was created. Direct energy transfer from the CdSe/CdS/ZnS single nanocrystal to the near-infrared (NIR) luminescent Nd(III) complex was observed and investigated by spectroscopic methods. The single-photon emission mode was confirmed for the novel hybrid source by Hanbury Brown and Twiss experiments.

Two new Sm 3+ complexes with pyrazolic β-diketones bearing a CF 3 group acting as main ligands and with 2,2'-bipyridine or 1,10-phenanthroline being the ancillary ligand were studied, and their energy level structure was established. Stark splitting observed in the photoluminescence spectra of the complexes points to their non-cubic symmetry, confirmed by the calculated Judd-Ofelt intensity parameters. Internal quantum yields obtained for the compounds by the Judd-Ofelt calculations were of the order of 5.5%, whereas the measured external quantum yields were 0.75% and 1.5% for Sm 3+ complexes involving 2,2'-bipyridine and 1,10-phenanthroline ancillary ligands, respectively, with the corresponding sensitization efficiencies calculated as 0.16 and 0.26. It was demonstrated that replacing the 1,10-phenanthroline ancillary ligand with 2,2'-bipyridine provides an increase in the intensity of 650 nm emission of the Sm 3+ complexes, with the branching ratio reaching 55%. Intensive emission of the studied complexes at 650 nm offers hope for their use as spectrally pure red emitters., (Copyright © 2019 Elsevier B.V. All rights reserved.)

We performed spectroscopic investigations of a novel tris(1,3-bis(1,3-dimethyl-1H-pyrazol-4-yl)propane-1,3-dionato)(1,10-phenanthroline) holmium (III) complex. It was demonstrated that bonding the corresponding ligand environment to Ho 3+ results in sensitization of the luminescence of the complex. The luminescence decay of the complex exhibits a biexponential behaviour. The short-lived component is attributed to the fluorescence of the ligand, whereas the long-lived component is connected with the Ho 3+ emission. Using fluorescence lifetime imaging, it was shown that there is a single type of emission sites in the studied complex. Based on the results of the optical measurements, the energy diagram for the investigated Ho 3+ complex was developed. It was shown that the energy transfer from the excited triplet level of the ligand environment to the 5 F 5 level of Ho 3+ is responsible for the emission of the ion in the complex., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The mechanochemical preparation of highly functionalized 3,5-disubstituted hydantoins was investigated in the presence of various poly(ethylene) glycols (PEGs), as safe grinding assisting agents (liquid-assisted grinding, LAG). A comparative study under dry-grinding conditions was also performed. The results showed that the cyclization reaction was influenced by the amount of the PEG grinding agents. In general, cleaner reaction profiles were observed in the presence of PEGs, compared to dry-grinding procedures.