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The new ligand 8,10-di-tert-butylbenzo[b][1,10]phenanthrolin-11-ol and its lanthanide complexes were obtained and their photoluminescence and electrochemical properties were studied.

The heteroligand complexes CpLn(BQ)2(DME) (BQ = 10-oxybenzo[h]quinoline, Cp = cyclopentadienyl, Ln = La (1), Nd (2), Sm (3), Gd (4)) were synthesised by the reaction of Cp3Ln with (BQ)H. The complexes of La, Nd and Sm were structurally characterised. In the case of ytterbium the reaction affords Cp2Yb(BQ)(DME) (5) and homoligand binuclear complex Yb2(BQ)6 (6) iregardless of the molar ratio of initial reagents. Upon UV excitation all the complexes gave rise to fluorescence of ligands in the visible region. The photoluminescent spectrum of compound 1 also contains a phosphorescent band with a lifetime longer than 10 ms. The complexes of Nd, Sm and Yb along with ligand emission display metal-centered luminescent f–f transitions.

Zinc complexes with oxyacridine ligands (Zn(Acr)2 and [Zn(Acr)Et]2) are synthesized, and their structures are determined by X-ray structure analysis (CIF files CCDC nos. 2063229 and 2063230, respectively). The complexes exhibit a medium-intensity emission with maxima at 700 and 630 nm upon photoexcitation (λ = 405 nm). Both compounds also manifest weak electroluminescence properties. The complexes with methyl substituents in the ligands are the most luminescence-active of the whole series of the synthesized zinc compounds with the oxyacridine ligands Zn(AcrR)2 and [Zn(AcrR)Et]2 (R = Me, Br, H). The results of the MTT assay show a moderate cytotoxic activity of the synthesized compounds.

Sm, Er, and Yb complexes containing anionic (4,5,6,7-tetrafluorobenzothiazol-2-yl)-2-(3,4,5,6-tetrafluoro)phenolate (SONF) and 3-(2-benzothiazol-2-yl)-2-naphtholate (NpSON) and neutral 1,10-phenathroline or 2,2'-bipyridine ligands were synthesized. The structures of complexes Yb(SONF)2-(NpSON)(DME)1.5 (II) and previously synthesized Er(SONF)3(DME) (I) were determined by X-ray diffraction (CIF files CCDC nos. 1972769 and 1972770, respectively). Upon excitation by light at λ 405 nm, all complexes showed luminescence of the ligands and Ln3+ ions. The OLED devices based on samarium complexes showed moderate intensi metal-centered emission of moderate intensity at a 19 V voltage.

Three new sterically hindered acridin-4-ols have been prepared by alkylation of anilines with 3,5-di-tert-butyl-6-methoxymethylcatechol followed by oxidation of the reaction mixture. Formation of the acridine moiety was found to occur in the course of oxidation of the intermediate (anilinomethyl)catechol on contact with air in the Et2O/H2O–KOH system. The molecular structure of two acridin-4-ols was determined by single-crystal X-ray diffraction.

The synthesis of complexes LnI(C6F5O)2 and LnCp(L)2 (Ln = Er, Yb; L = C6F5O, SONF), which are convenient precursors for the preparation of heteroligand bimetallic complexes, is described. The structures of YbI(C6F5O)2(DME)2 (I), CpEr(C6F5O)2(DME)[(C2H5)2O] (III), and CpYb(SONF)2(DME) (VI) were established by X-ray diffraction (CIF files CCDC (nos. 1902963 (I), 1902964 (III), and 1902965 (VI)). The developed methods were used to prepare heteroligand bimetallic Yb(III)–Er(III) complexes (C6F5O)2Yb[µ-(CF3)2CHO]2Er(C6F5O)2 and {(SONF)2Yb[µ-(CF3)2CHO]2-Er(SONF)2}x, which showed metal-centered emission inherent in Yb3+ and Er3+ ions λem = 985 and 1540 nm, respectively. This suggests that the obtained compounds can serve as promising upconversion materials.

Temperature dependences of the saturated vapor pressure of lanthanum complexes based on 2-(2-benzoxazol-2-yl)phenolate ligand have been obtained using the Knudsen effusion method. The thermodynamic parameters of vaporization have been calculated from the p−T data. Mass spectra and differential scanning calorimetry data have been obtained.

The complexes of La, Ce, Nd, Sm, Eu, Tb and Yb with benzoxazolyl-phenolate, benzothiazolyl-phenolate, benzoxazolyl-naphtholate, benzothiazolyl-naphtholate and 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione ligands were treated with n,γ-irradiation upon a sustained (45 h, absorbed dose of 120 krad, flux of neutrons 5·1013 n/cm2) and a pulse mode (3 ms, absorbed dose of 130 krad, flux of neutrons 3.6·1013 n/cm2). It was found that main characteristics of the compounds (shape of substance, color, IR absorption and photoluminescent spectra) have not changed. With an example of cerium complex [Ce(OON)3]2 it was revealed that the molecular structure of compounds after strong pulse irradiation also does not changed. However, computer simulations of neutron exposure on the same complexes showed significant shift of metal atoms and ligands. Possible reasons for the detected discrepancy between experimental and calculated data are discussed.

The calculation of defects in the structures of the Sc, La, Nd, Sm, Tb, and Yb complexes with substituted phenolate and naphtholate ligands formed under the action of neutrons with a mean energy of 2 MeV shows that the shifts of the target atoms depend on their masses and can achieve 1 μm for O, N, and S. A similar result is obtained for the calculation of the destruction of the Eu(TTA)3(DME)2 complex (HTTA is thenoyltrifluoroacetone). However, the treatment of the samples with the n,γ radiation does not result in destruction. Possible reasons for the found divergence between the calculated and experimental data are discussed.

A comparative study of the photoluminescence (PL) and radioluminescence (RL) of lanthanide complexes with benzimidazolylphenolate (NON), 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedionate (TTA) and 1,3-acetylacetonate (acac) ligands revealed significant differences in the total and relative intensity of emission. The PL spectra contain both bands of metal-centered and ligand centred emission while X-ray excited compounds display only the bands of Ln3+ ions, the relative intensity of which differs from that in UV excited analogues. The RL intensity of all the studied complexes is about 300 times lower than that of PL. Increasing the cathode current and tube voltage enhances the RL efficiency insignificantly. Simultaneous irradiation of the sample with X-ray and UV radiation leads to a corresponding increase in the intensity of emission. A possible mechanism of RL of organo-lanthanide complexes is discussed.

A series of homo and heterometallic La, Li and Na complexes with 2-(2-benzoxyazol-2-yl)phenolate (L) ligands were synthesized using La[N(SiMe3)2]3 and M[N(SiMe3)2] (M = Li, Na) or La(Cp)3 as starting materials for La2(L)6 (1), La2(L)6(bipy) (2), La(L)2Cp(DME) (3), La2Li(L)7 (4), Li(L) (5), Na(L) (6). Photoluminescent (PL) properties of these compounds, staring phenol H(L) as well as previously obtained complex LaNa(L)4(DME)2 (7) were studied at 300 and 77 K. Molecular structure of 2, 3 and 4 were determined by X-ray analysis. All the compounds in THF solution at 300 K upon UV excitation (370 nm) revealed a bright fluorescence in the range 430–460 nm and moderate phosphorescence as a shoulder at about 500 nm. The total quantum yield (QY) is 1–35%. At 77 K all lanthanum compounds (except 3) in THF solution exhibit weak or moderate fluorescence but intense phosphorescence (τ 3.5 – 95.8 ms). The PL spectra of solid samples at 300 K strongly differ from those of solutions, apparently due to the effects of crystal packing, the shape and size of the crystals. The emission of H(L) is most intensive but the PL of 1 has lowest efficiency. It is assumed that phosphorescence occurs from excimers and exciplexes, the formation of which in the compounds studied has been confirmed by X-ray diffraction analysis.

In the search for a way to organic up-converter materials the complex [(OON)2Er(THF)](μ-O)[(OON)2Yb(THF)] with the (benzoxazol-2-yl)phenolate (OON) ligand was synthesized. Upon excitation by laser with λex 405 nm light the complex displayed only emission of the Yb3+ ion indicating the lack of energy transfer from Yb to Er. To develop a method for preparation of other up-converter materials the complexes [Yb4(SON)8(μ4-O)(OH)2 and [Eu4(OON)10Li2(3-O)2] with (benzothiazol-2-yl)phenolate (SON) and (benzoxazol-2-yl)phenolate ligands were synthesized using water as a co-reagent. The X-ray study revealed that the clusters contain μ2-O, μ3-O and μ4-O bridges and short Ln…Ln contacts. These modelling syntheses showed that the method is applicable for preparation of potential up-convertion materials with Ln-O-Ln’ groupings.

In an attempt to get more insight into the way of formation of recently obtained unusual iodide-sulfide-nitride clusters Ln 3 I 5 (S 2 )(S 2 N 2 )(THF) 10 (Ln = Nd ( 1 ), Dy ( 2 )) and modify this synthesis reactions of dysprosium iodide-nitride with sulfur were carried out in various conditions. It was found that the reaction of as prepared dysprosium iodide-nitride [(DyI 2 ) 3 N] x with sulfur in THF yields ionic complex {[DyI 2 (THF) 5 ] + [DyI 2 S 5 (THF) 2 ] − } ( 3 ) anionic part of which contains six-membered cycle DyS 5 . The same reaction in iso -propylamine medium affords ionic iodide-sulfide{[( i PrNH 2 ) 4 Dy(μ- η 2 :η 2 - S 2 )] 2 } 2+ [I − ] 2 ( 4 ) containing bipyramide core formed by two apical Dy 3+ cations and two equatorial S 2 fragments. The nitride [(DyI) 3 N 2 ] in THF does not interact with sulfur but upon addition of triiodide DyI 3 the reaction affords cluster 2 in moderate yield.

A set of new heterometallic complexes of composition of ErYb(L) 6 and Er 0.67 Yb 1.33 (L) 6 (L = 3-(2-benzothiazol-2-yl)-2-naphtholate (NpSON), pentafluorophenolate (C 6 F 5 O) and hexafluoro-iso-propoxide ((CF 3 ) 2 CHO) were synthesized and characterized by X-ray diffraction (L= (CF 3 ) 2 CHO), MALDI-TOF, 19 F NMR (L= C 6 F 5 O, (CF 3 ) 2 CHO), IR and elemental analyses. All the compounds exhibited emission of Er 3+ at 1530 nm upon direct excitation of Yb 3 + by the laser irradiation with λ ex = 910 and 980 nm that shows the intramolecular energy transfer Yb 3+ →Er 3+ . In the luminescence spectra of Er 0.67 Yb 1.33 [(CF 3 ) 2 CHO] 9 besides the band at 1530 nm the short-wavelength emission at 550 nm was found, which indicates upconversion phenomenon. Excitation of ytterbium in the mixture of monometallic iso -propoxides Er 2 [(CF 3 ) 2 CHO] 6 and Yb 2 [(CF 3 ) 2 CHO] 6 does not lead to luminescence of erbium ions which confirms intramolecular character of energy transfer in Er 0.67 Yb 1.33 [(CF 3 ) 2 CHO] 6 .

The syntheses of the 2,6-di-tert-butyl-4-(2-hydroxybenzylideneamino)phenolate (L) complexes of Gd (I), Nd (II), Er (III), Yb (IV), Tm (V), Sm (VI), and Tb (VII) are described. The structures of the Gd and Er complexes are determined by X-ray diffraction analysis (CIF files CCDC nos. 1558820 (I) and 1558819 (III)). All synthesized compounds exhibit ligand-centered photoluminescence in a range of 405–485 nm. In addition, the luminescence spectra of solid samples of the neodymium and ytterbium complexes contain narrow bands of f–f transitions characteristic of Nd3+ and Yb3+ ions.

In search of new fully fluorinated ligands which effectively sensitized the lanthanide luminescence the 4,5,6,7-tetrafluoro-1,3-benzothiazol-2(3Н)-thione (HmbtF) was proposed. Based on this ligand a set of new complexes LnL3(THF)2 (Ln1) (Ln = Nd, Gd, Tb, Dy, Er, Yb) was synthesized and their luminescence were studied. The structure of the compounds was established with an example of Gd derivative. The triplet state energy of mbtF was found to be 21500 cm−1 that enables the resonant energy transfer to Dy3+, Tb3+, Nd3+ and Er3+ ions and stipulates metal-centered emission of some complexes. In case of Yb1 the observed luminescence of Yb3+ ion probably occurs due to the non-resonant energy transfer.

A number of new zinc complexes with 1,3-di‑tert‑butyl‑7-methylacridin-4-olate or 1,3-di‑tert‑butyl‑7-bromoacridin-4-olate ligands Zn(AcrMe)2, Zn(AcrMe)2(DMSO), Zn(AcrMe)2(Py)2, [Zn(Et)(AcrMe)]2, Zn(AcrBr)2, Zn(AcrBr)2(DMSO) and [Zn(Et)(AcrBr)]2 were synthesized by the reaction of respective acridinol with Et2Zn and structurally characterized. All compounds exhibited photoluminescence in the form of a single band in the 600 - 700 nm region. Compounds Zn(AcrMe)2 and [Zn(Et)(AcrMe)]2 displayed also weak electroluminescent properties. It is found that introduction of both alkyl or bromine substituents into acridine rings cause the hypsochromic shift of emission band. The resistance of organozinc complexes to strong ionizing radiation was studied using the example of [Zn(Et)(AcrMe)]2. X-ray diffraction study showed that the molecular structure of the complex did not change after strong neutron-gamma irradiation for 45 h.

A series of rare-earth metal carboxylates M(RCOO) 3 (M = La ( 1 ), Eu ( 2 ), Gd ( 3 ), Tb ( 4 ), Er ( 5 ); R = 3,5-di- tert -butyl-4-hydroxyphenyl) was synthesized and characterized by elemental analysis, NMR, IR spectroscopy and MALDI-TOF spectroscopy. The photoluminescent (PL) properties of 1 – 5 were investigated. The electron transfer reactions were examined in CUPRAC-test. The radical scavenging activity of the complexes was measured spectrophotometrically using a DPPH-test. The EC 50 values for complexes are varied from 32 to 57 μM while the EC 50 for RCOOH is 79 μM. The inhibition of lipoxygenase (LOX-1B) in the presence of compounds was evaluated. It was found that complexes are weak inhibitors, while RCOOH is inactive. The lanthanum complex was found to be the most efficient inhibitor of lipoxygenase. Thus, the lanthanide carboxylates with 2,6-di- tert -butylphenol moiety could be used as potential antioxidants and luminescent materials.

Herein, complexes [ZnL]2 (1), {(H2O)Zn(μ-L)Yb[OCH(CF3)2]3} (2), {[(CF3)2HCO]Zn(μ-L)Yb[OCH(CF3)2](μ-OH)}2 (3), and [(H2O)Ln2(L)3] (Ln = Yb (4) and Gd (5)) containing a bridging Schiff-base ligand (H2L = N,N'-bis(3-methoxy salicylidene)phenylene-1,2-diamine) were synthesized. The compounds 1-4 were structurally characterized. The ytterbium derivatives 2-4 exhibited bright NIR metal-centred photoluminescence (PL) of Yb3+ ion under one- (λex = 380 nm) and two-photon (λex = 750 nm) excitation. The superior luminescence properties of complex 2, which was suggested as a marker for NIR bioimaging, were explained via the strong absorption of the 375 nm LMCT state of the ZnL chromophore, efficient energy transfer from ZnL towards Yb3+ through a reversible ligand-to-lanthanide electron transfer process, and absence of luminescence quenchers (C-H and O-H groups) in the first coordination sphere of the rare-earth atom.

Heterometallic complexes Ln(L1)5Zn (Ln = Sc, Sm, Gd) were obtained by the reactions of silylamides Ln[N(SiMe)2]3 with 2-(benzoxazol-2-yl)phenol (HL1) in the presence of diethylzinc. Similar reactions with 3-(benzothiazol-2-yl)-2-naphthol (HL2) led to the formation of complexes Ln(L2)5Zn (Ln = Nd, Er, Gd, Yb). The introduction of the zinc-containing fragments provided a considerable increase of photo- and electroluminescence intensity of the scandium complex.

The cathodoluminescence (CL) of organo-lanthanide complexes is studied as a modeling of beta luminescence. It is found that complexes of Sc, La, and lanthanides with anionic OO, ON bidentate and O-monodentate ligands under excitation by fast electrons display luminescence of various intensities. In the spectra of Sc, La, Nd, Er, and Tm compounds, only broadened bands of the ligands peaked about 450 nm are observed. A similar spectrum gives anthracene, which is used as a reference compound. In contrast, the emission spectra of Eu and Tb compounds contain only the narrow bands of f–f transitions characteristic of these metals. The spectra of Sm, Dy, and Yb derivatives exhibit both the bands of ligands and weak metal-centered luminescence. X-ray luminescence (RL) of several terbium complexes is also investigated. A comparison of the photoluminescence, CL and RL spectra of the studied compounds reveals a similarity of the shape of the spectra but a significant difference in their intensities. Terbium compounds show record scintillating activity. Possible mechanisms of luminescence of organo-lanthanide complexes upon different types of excitation are discussed.

Alkoxides [Ln(OR)3(DME)]2 (R = CH(CF3)2, Ln = Sm (1), Yb (2)), [Ce(OR)3(Phen)]2 (3) (Phen = 1,10-phenanthroline), [Ce(OR′)3(DME)2]2 (R′ = C(CF3)3) (4), {Gd(OR′)3(DME)2} (5), {Ln2[O(CF3)2C–C(CF3)2O]3} (Ln = Ce (6), Gd (7)), {Ce2[O(CF3)2C–C(CF3)2O]3(Phen)2} (8), and {Ce[O(CF3)2C–C(CF3)2O][O(CF3)2–C(CF3)2OH](Phen)2} (9) were synthesized by the reactions of silylamides Ln[N(SiMe3)2]3 with respective fluorinated alcohols. The heterovalent trinuclear complex {Sm2(μ2-OR)3(μ3-OR)2Sm(OR)2(THF)2.5(Et2O)0.5} (10) was obtained by treatment of SmI2(THF)2 with ROK. The reaction of europium(II) and yttrium(III) silylamides with ROH afforded the heterobimetallic alkoxide {Eu2(μ2-OR)3(μ3-OR)2Y(OR)2(DME)2} (11) containing divalent europium. The molecular structures of 1, 2, 3, 9, 10 and 11 were determined by X-ray analysis. All the prepared cerium derivatives as well as the europium–yttrium isopropoxide upon UV excitation exhibited photoluminescence in the regions of 370–425 (for Ce3+) and 485 nm (for Eu2+) which was assigned to 4d→5f transitions.

Photoluminescent (PL) and electroluminescent (EL) properties of heteroleptic complexes of Yb 3+ containing the 3-(2-benzothiazol-2-yl)-2-naphtholate (L), 8-oxyquinolate (Q), pentafluorophenolate (OC 6 F 5 ), or cyclopentadienyl (Cp) ligands were studied. All the complexes revealed NIR emission of Yb 3+ ion of different intensity. The obtained data indirectly confirm the fact that the excitation of the ytterbium in naphtholate complexes proceeds due to intramolecular reduction–oxidation mechanism.

A set of Y, Nd, Tm and Yb complexes containing, along with 3-(2-benzothiazol-2-yl)-2-naphtholate (L), the 8-oxyquinolate (Q), pentafluorophenolate, cyclopentadienyl (Cp) or methylcyclopentadienyl (CpMe) ligands were synthesized using Ln[N(SiMe3)2]3, Ln(Cp)3 or Ln(CpMe)3 as starting materials. Depending on molar ratio of initial reagents the mononuclear, dinuclear or tetranuclear products were isolated from the reaction mixtures. The complexes Y2(L)4(CpMe)2, Nd2(L)4(Cp)2, Yb(L)(Cp)2, Y2(L)3(Q)2(CpMe) and Y4(L)(Q)11 were structurally characterized. The synthesis routes and conditions governing the set of ligands in products and their nuclearity are discussed.

A series of lanthanide complexes (Ln = Nd, Sm, Eu, Gd and Yb) with anionic 2-mercaptobenothiazolate (mbt) ligands were synthesized. Depending on the solvents chosen for the synthesis, Ln(mbt)3(THF)2 and Ln(mbt)3(Et2O) complexes were precipitated from THF and Et2O solutions respectively. The structure of Yb(mbt)3(Et2O) was determined by X-ray analysis. Photophysical properties of the complexes were studied. It was found that under photoexcitation Nd and Yb derivatives exhibit bright metal-centered luminescence in the NIR region while Sm(mbt)3(THF)2 demonstrates intensive visible emission corresponding to (4)G5/2 → (6)HJ (J = 5/2, 7/2, 9/2, 11/2) f-f transitions of Sm(3+) along with NIR emission of moderate intensity. In the case of europium compounds as well as Sm(mbt)3(Et2O) no luminescence was detected. It is assumed that the difference in photoluminescence of Yb and Eu complexes can be explained by an intramolecular electron transfer process, which efficiently proceeds in these compounds.

Herein, complexes [ZnL]

Unprecedented complexes of the composition Ln3I5(S2N2)(S2)(THF)10 were obtained in the reactions of neodymium and dysprosium iodide-nitrides with sulfur. The inorganic core of the molecules contains the cyclic fragments Ln(μ-S2)Ln, LnSNSN and LnSN. Ten of the fourteen atoms of the core are coplanar, the remaining four S2 and I2 atoms lie in the other two orthogonal planes. The dysprosium complex upon excitation with UV light exhibits the metal-centered luminescence characteristic of the Dy(3+) ion. Geometric parameters of the molecules, computational data, electron spectroscopy and fluorescence suggest the existence of some conjugation in the mentioned heterocycles.