Structure and photophysical properties of new trinuclear lanthanide complexes (Ln = Eu and Tb) with 1,10-phenanthroline

Examples of trinuclear lanthanide (Ln) complexes using bridging sulfato and hydroxo ligands for Ln = Eu and Tb are reported. Structural data demonstrate that three nine-coordinate Ln³⁺ ions are caged in a monomeric structure in [Ln₃(phen)₃(OH)(SO₄)₄(DMF)₃] · DMF · H₂O, with Ln?Ln distances slightly greater than 4 Å. The luminescence and excitation spectra have been recorded and interpreted.     

Structures and photoluminescence of coordination polymers assembled from bifunctional ligand containing both tetrazole and imidazole groups

Three new coordination polymers, namely, {[Cu₂(IPT)(SO₄)(OH)(H₂O)]·H₂O}_n (HIPT = 5-(4-(1H-imidazol-1-yl)phenyl)- 1H-tetrazolate, 1), {[Cd₂(IPT)(NPA)(OH)]·H₂O}_n (H₂NPA = 5-nitroisophthalic acid, 2), and {[Zn₂(IPT)(IDC)(H₂O)]·3H₂O}_n (H₃IDC = 1H-imidazole-4,5-dicarboxylic acid, 3), were assembled from a bifunctional organic ligand containing both tetrazole and imidazole groups with/without the aid of carboxylate coligands. Compound 1 possesses 2D structure built by 1D [Cu₂(IPT)(SO₄)(OH)]_n secondary building blocks and IPT⁻ linkers. The 2D networks are linked into 3D supramolecular framework via water chains in helical conformation. Compound 2 displays 3D pillar-layer framework with 2D layers based on tetranuclear Cd(II) SBUs and NPA^2 − pillars. Compound 3 exhibits a 3D framework constructed from the interconnection of 1D [Zn-IDC]_n chains and binuclear Zn₂(IPT)₂ rings. The thermal stabilities of porous compound 3 and luminescent properties of compounds 2 and 3 have also been studied in detail. They exhibit intense solid-state fluorescent emissions at room temperature.     

Syntheses,crystal structures and luminescence properties of lanthanide coordination polymers involving in situ C–S bond cleavage of (4-pyridylthio)acetic acid

Lanthanide coordination polymers with the formula [Ln₂(C₂O₄)₃(H₂O)₆]_n (1) (Ln = Nd, 1) and [Ln₂(C₂O₄)₃(pythioH)₂(H₂O)₂]_n (Ln = Eu 2; Dy 3; Er 4) pythio = 4-pyridinethiolate) were synthesized by treating Ln^III nitrates with (4-pyridylthio)acetic acid under hydrothermal conditions. Single-crystal X-ray diffraction studies indicate that these lanthanide coordination polymers consist of extended oxalate-bridged two-dimensional layer structure. Interestingly, in situ C–S bond cleavage occurred and (4-pyridylthio)acetic acid was transformed into 4-pyridinethiolate and oxalate. The complexes 2 and 3 display strong fluorescent emission in the solid state at room temperature.     

Polycatenated (4, 4) lanthanide(III) coordination networks based on apidate: Synthesis,structure and properties

Three rare earth coordination polymers, {[Ln₂(μ₃-ADI)₂(μ₂-ADI)(H₂O)₄]·H₂O}_n (Ln = Tb, 1; Eu, 2; Er, 3; ADI = adipate), which show the inclined interpenetration of (4, 4) nets and bright luminescence, were isolated from H₂PDC-assisted (H₂PDC = pyridine-2,3-dicarboxylatic acid) hydrothermal reactions of H₂ADI and Ln₂O₃.     

1D chain lanthanide coordination polymers with 6-hydroxynicotinic acid: Crystal structures and luminescent properties

Four new lanthanide coordination polymers {[Ln(HL)₂(H₂O)₅] · HL ·  H₂O}_n (Ln = Sm for 1, Eu for 2, Tb for 3 and Dy for 4) (H₂L = 6-hydroxynicotinic acid) have been synthesized and characterized by elemental analysis, FT-IR spectra and X-ray single-crystal diffraction. They all exhibit 1D chain structure, which are further linked via hydrogen bonds to form 3D supramolecular architecture. Luminescent properties of these lanthanide coordination polymers are studied.     

Two kinds of 3D coordination frameworks from monometallic to 4d–4f heterometallic: Synthesis,crystal structures,photoluminescence and magnetic properties

Two kinds of three-dimensional (3D) coordination frameworks from monometallic to heterometallic, including a charming 3D monometallic complex, namely, [Eu₂(mpda)₃(H2O)₄]_n (1) and the first series of novel 3D heterometallic 4d–4f coordination frameworks based on 2,6-dimethylpyridine-3,5-dicarboxylic acid, namely, [Ln₂Cd₂(mpda)₂(bdc)₂(SO₄)₂(H2O)₆]_n [Ln = Sm(2), Eu(3), Gd(4), Tb(5), Dy(6); mpda = 2,6-dimethylpyridine-3,5-dicarboxylic acid; bdc = 1,4-benzenedicarboxylic acid] have been successfully synthesized under hydrothermal conditions and structurally characterized. Crystal 1 is featured by its interesting 3D chain-layer construction which is formed by the alternative arrangement of chains and layers and exhibits 2-nodal 5, 6-connected 3D network with the Schlafli symbol of {3³.4³.5⁵.6⁴}{3⁶.4⁶.5³}. Complexes 2–6 are isostructural and it reveals that these 3D heterometallic compounds are firstly built by H₂mpda ligand. What is worth mentioning is that anionic ligand SO₄^2 − plays a crucial function in the construction building. The two-dimensional (2D) lanthanide-transition heterometallic bilayers [Ln₂Cd₂(mpda)₂(bdc)₂]_n are pillared by SO₄^2 − subunits forming mixed-ligand complexes with a pillared-layer 3D structure. Complexes 2–6 feature 4-nodal 3, 4, 5, 6-connected 3D frameworks with {4.8²}{4.8⁴.10}{4².8¹⁰.10².12}{4².8⁸} topology. All the complexes are characterized by elemental analyses, FT-IR spectroscopy, Powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). Furthermore, the luminescence properties of compounds 1, 3, and 5 and the magnetic properties of complexes 4 and 6 were also investigated in detail.     

Syntheses and physical properties of three-dimensional coordination polymers with the flexible tripodal ligand 1,3,5-tris(1,2,4-triazol-1-ylmethyl)benzene

Two 3D organic–inorganic hybrid coordination polymers, [M₂(ttmb)₂(SO₄)₂(H₂O)₂] · 7H₂O (M = Cd, 1; M = Mn, 2; ttmb = 1,3,5-tris(1,2,4-triazol-1-ylmethyl)benzene), have been synthesized and structurally characterized. They are isostructural and possess a 3D architecture fused from 2D (4,4) M(ttmb) networks and MSO₄ chains by sharing “hinge” metal atoms. The thermal properties of 1 and 2, luminescent property of 1 as well as magnetic property of 2 have been investigated.     

Two novel 2D organic–inorganic hybrid silicotungstates assembled by {Cu2Ln2(ox)(SiW11)2} dimers and [Cu(en)(ox)]/[Cu(en)2] linkers

Two novel 2-D organic–inorganic hybrid silicotungstates [H₂en][Cu(en)₂(H₂O)]₂{[Cu(en)₂]₃[Cu(en)(ox)]₂[Ln₂(ox)(α-SiW₁₁O₃₉)₂]}·nH₂O (Ln = Er^III, n = 10 for 1, Ln = Sm^III, n = 8 for 2) with mixed organic ligands of ox and en (ox = oxalate, en = ethylenediamine) have been hydrothermally synthesized and characterized by IR spectrum, thermogravimetric analysis (TGA), power X-ray diffraction (PXRD) and X-ray single-crystal diffraction, respectively. Notably, 1 and 2 are isomorphic and exhibit the first novel 2D organic–inorganic hybrid silicotungstates assembled by {Cu₂Ln₂(ox)(SiW₁₁)₂} dimers and [Cu(en)(ox)]/[Cu(en)₂] linkers. Furthermore, the TG curve of 1 and 2 display three steps of weight loss in the range of 25–1000 °C.     

Spectroscopic studies on bis(1-amidino-O-alkylurea) copper(II) sulfate complexes where alkyl = methyl,ethyl, n-propyl or n-butyl: EPR evidence for binuclear complexes

Four new Cu(II) Complexes viz. [Cu(II)(1-amidino-O-methylurea)₂]SO₄·2H₂O (1), [Cu(II)(1-amidino-O-ethylurea)₂](SO₄)₂·2H₂O (2), [Cu(II)(1-amidino-O-n-propylurea)₂] SO₄·2H₂O (3), [Cu(II)(1-amidino-O-n-butylurea)₂]₂(SO₄)₂·2H₂O (4) have been synthesized and characterized. EPR spectrum of complex 4 at RT consisted of fine-structure transitions (ΔMs = ±1) with zero-field splitting (ZFS) of 0.0485 cm^?1 and a half-field signal (ΔMs = ±2) at ca. 1600 G, revealed formation of binuclear complex (S = 1). Whereas EPR spectrum of complex 2 in DMSO showed a mixture of mononuclear and binuclear complex in the ratio 0.75:1.0 with ZFS of 0.0385 cm^?1. From the temperature dependence of the EPR signal intensity, the isotropic exchange-interaction constant J was evaluated.     

Novel silver(I) compounds assembled from hybrid ligands based on linear or T-shaped coordination environment

Two novel 1D compounds {[Ag₃(Hbptc)(bpa)₂]·H₂O}_n (1) and [Ag₂(H₂bptc)(bpp)₂]_n (2) (H₄bptc = 3,3′,4,4′-benzophenonetetracarboxylic acid, bpa = 1,2-bis(4-pyridyl)ethane and bpp = 1,3-bis(4-pyridyl)propane) were synthesized and structurally characterized. The crystal structures of compounds exhibit two kinds of ladder-like chains based on linear or T-shaped coordination environment of Ag(I). Fluorescence spectra of compounds 1 and 2 indicate the unusual intensity of fluorescent emission upon photoexcitation which may be attributed to ligand-to-metal charge transfer and Ag–Ag interactions.     

Construction of three-dimensional Ln–Ag (Ln = Eu; Tm) coordination polymers based on isonicotinate and oxalate ligands

Hexanuclear 4d–4f heterometallic coordination polymers, [Ln₂Ag₄(IN)₅(ox)₂(NO₃)(H₂O)₂ · 3H₂O] [Ln = Eu (1), Tm (2); IN = isonicotinate and ox = oxalate], have been synthesized by hydrothermal reaction of mixed organic ligands and metal salts. Both structures display the same unusual 3D heterometallic coordination frameworks based on rare zigzag lanthanide–oxalate–silver chains, Ag₂(IN)₃ units and IN linkers. The photoluminescent properties of complex 2 were studied.     

Two different Zn(II) interpenetrating networks derived from different dicarboxylate ligands mixed with a flexible imidazole-based ligand

Two interpenetrating networks based on 1,4-bis(2-methylimidazol-1-ylmethyl)-2,3,5,6-tetramethylbenzene (bmimx), namely, {[Zn₂(bmimx)₂(cba)₂]·2.5H₂O}_n (1) and {[Zn(bmimx)(suc)]·2H₂O}_n (2) (H₂cba = 4,4′-carbonyldibenzoic acid, H₂suc = succinic acid) have been prepared at hydrothermal condition by varying the dicarboxylate ligands. Single-crystal X-ray diffraction indicates that complex 1 shows a 4-connected dmp net with 3-fold interpenetration which contains 1D (Zn − cba)_n right- and left-handed helical chains; complex 2 shows a dia topology with 4-fold interpenetration. The results indicate that the spacers of dicarboxylate coligands have an important effect on the interpenetrating characters and ultimate frameworks. Moreover, the photoluminescence properties of the two complexes were studied in the solid state at room temperature.     

Near-infrared (NIR) luminescent homoleptic linear tetranuclear [Ln4((OH)2-Salophen)4] (Ln = Nd or Yb) complexes self-assembled from the dihydroxylated Salophen ligand

Through self-assembly of the (OH)₂-Salophen H₄L (H₄L = N, N′-bis(3-hydroxyl salicylidene)benzene-1,2-diamine) with LnCl₃·6H₂O (Ln = La, Nd, Yb, Er or Gd), series of [Ln₄((OH)₂-Salophen)₄]-arrayed complexes [Ln₄(H₂L)₂(L)₂(EtOH)₂] (Ln = La, 1; Ln = Nd, 2; Ln = Yb, 3; Ln = Er, 4 or Ln = Gd, 5) were obtained, respectively. The result of their photophysical properties shows that the strong and characteristic NIR luminescence for complexes 2–3 with emissive lifetimes in microsecond ranges is observed, and the sensitization arises from the excited state (¹LC) of the (OH)₂-Salophen ligand despite the luminescent quenching with OH-oscillators around the Ln^3 + ions.     

Six isostructural lanthanide-containing MOFs built on a semi-rigid tripodal organic ligand

By using a semi-rigid tripodal ligand 1,1′,1′′-(2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene)tripyridinium-4-olate) (L), six isomorphous lanthanum metal-organic frameworks (MOFs), namely, [Pr(L)₂(Cl)₂]·(Cl)(DMF)_0.5·(H₂O)·(1), [Nd(L)₂(Cl)₂]·(Cl)(2), [Tb(L)₂(Cl)₂]·(Cl)·(DMF)·(H₂O)(3), [Eu(L)₂(Cl)₂]·(Cl)(DMF)·(H₂O)(4), [La(L)₂(Cl)₂]·(Cl)(5), [Sm(L)₂(Cl)₂]·(Cl) (DMF)·(H₂O) (6), were obtained and characterized by single crystal X-ray diffraction, IR and elemental analysis. Six compounds are isostructural with Ln^3 + (Ln = Pr, Nd, Tb, Eu, La, Sm) and in which the Ln^3 + is considered as a 6-connecting node and the L ligand is a 3-connecting node to afford a (3,6)-connected 2D layer with kgd topology, which further stacks into 3D supramolecular networks through C-H^…O weak interactions. Luminescent properties of these lanthanide MOFs have also been assessed at ambient temperature, in which the Pr^3 +-1 and the La^3 +-5 are slightly blue-shifted with respect to the ligand. Series of sharp peaks characteristic of the Eu^3 +-4, the Tb^3 +-3 and Sm^3 + − 6 metal-centered luminescence appear. The Nd^3 +-2 has no emission.     

Three dimensional lanthanide-organic frameworks containing tetranuclear Ln (Ln = La,Nd) cluster secondary building blocks

The hydrothermal reactions of Ln₂O₃, o-phthalic acid (H₂L₁) and N,N’-Piperazine(bis-methylene phosphonic acid) hydrochloride (H₄L₂·HCl) yielded two three dimensional (3D) lanthanide-organic frameworks formulated as [Ln₄(L₁)₂(H₂L₂)₃(H₃L₂)₂]·18H₂O (Ln = La, 1; Nd, 2). Single-crystal X-ray diffraction revealed that they are isostructural. They feature 3D open framework structures containing rarely observed centrosymmetric tetranuclear lanthanide sub-building units (SBU). The photoluminescence property of 2 has been investigated, and it shows strong solid-emissions in the near-infrared region at room temperature.     

A novel three-dimensional 3d–4f heterometallic coordination polymer with unique (3,4)-connected topology and helical units: Synthesis,crystal structure and photoluminescence property

One new three-dimensional 3d–4f heterometallic coordination polymer, namely, {[EuZn₂(imdc)₂(C₂O₄)_0.5(H₂O)₄]·2H₂O}_n (1) (H₃imdc = imidazole-4,5-dicarboxylic acid), has been successfully synthesized by the hydrothermal reactions of Eu₂O₃, Zn(NO₃)₂·6H₂O, H₃imdc, H₂C₂O₄·2H₂O and H₂O. Single-crystal X-ray diffraction analysis reveals that complex 1 possesses 3D heterometallic framework containing 2D layer based on L–Zn2–L (L = imdc) helical chains and L–EuZn1–L chains. Complex 1 exhibits unprecedented (3,4)-connected four-nodal topology with Schläfli symbol (6·7·8) (6·7·9) (6·7²·8²·10) (7·8²). Moreover, the photoluminescence property of 1 was investigated in the solid-state at room temperature.     

Two new 3-D coordination polymers with 5-tert-butyl isophthalic acid and flexible N-donor co-ligands bearing linear trinuclear secondary building blocks

Two new 3-D coordination polymers bearing linear trinuclear secondary building blocks with mixed bridging ligands, {[Ni₃(tbip)₂(Htbip)₂(bib)₂]·4H₂O}_n (1) and {[Co₃(tbip)₂(Htbip)₂(btb)₂]·4H₂O}_n (2) (H₂tbip = 5-tert-butyl isophthalic acid, bib = 1,4-bis(imidazol-1-yl)butane, btb = 1,4-bis(1,2,4-triazol-1-yl)butane), were obtained and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, single-crystal X-ray crystallography and powder X-ray diffraction. Both complexes 1 and 2 display similar 3D 6-connected pcu networks containing the linear trinuclear [M₃(COO)₆] (M = Ni and Co) clusters as nodes.     

Three unprecedented high-connected 3D lanthanide–organic frameworks based on benzene-1,2,4,5-tetracarboxylic acid

Three unprecedented high-connected 3D lanthanide coordination polymers based on benzene-1,2,4,5-tetracarboxylic acid (H₄bta), {[Ln₂(bta)_1.5(H₂O)₄] · 3H₂O}_n (Ln = La (1) and Ce (2)) and [Pr(bta)_0.5(H₂bta)_0.5(H₂O)]_n (3), have been synthesized under hydrothermal conditions. Complexes 1 and 2 show trinodal (4,4,10)-connected 3D network structures consisting of tetranuclear metal clusters bridged by bta^4 − ligands, and a chair conformation hexamer water cluster can be found within the cage enclosed by eight neighboring tetranuclear metal clusters in the two complexes. While 3 consists of 2D {Pr(bta)_0.5}_n layers linked by H₂bta^2 − ligands, resulting in an unprecedented trinodal (4,6,10)-connected 3D topological network. The organic ligand exhibits five kinds of coordination modes, in which one of them is reported for the first time. Moreover, the luminescent properties of 1–3 have also been investigated.     

Three cobalt (II) complexes with triethylenetetraaminehexaacetic acid: From binuclear complex to 3d-4f coordination polymers

The cobalt(II)–lanthanide(III) heteronuclear complexes [Ln(H₂O)₄Co₂(TTHA)(SCN)₂]·H₃O⁺ (H₆TTHA = triethylenetetraaminehexaacetic acid, Ln = La(2), Ce(3)) have been synthesized based on a binuclear building block of [Co₂(H₂TTHA)(H₂O)₂] in [Co₂(H₂TTHA)(H₂O)₂]·4H₂O (1). Single-crystal structures show that complex 1 is a binuclear complex, containing the [Co₂(H₂TTHA)(H₂O)₂] unit as a useful building block. Adding the La^3 + and Ce^3 + ions to this synthesis system, two new 3d-4f mixed complexes 2 and 3 were obtained. Complexes 2 and 3 show 3D framework, comprising an infinite 1D (one-dimensional) chain based on heterometallic Ln₂Co₂ (Ln = La(2), Ce(3)). Further investigations such as IR spectra, UV–vis spectra, TGA, XRD and magnetic properties were studied.     

Absolute helicity of 1D chains influenced by enantiopure ligands

Two novel coordination polymers, [Cd(D-1-Hcam)(nta)(H₂O)₂]₂[Cd(D-3-Hcam)(nta)(H₂O)₂]₂·4H₂O (1) and [Cd(DL-Hcam)(nta)(H₂O)₂]·H₂O (2) (D-1-Hcam/D-3-Hcam = monodehydrated d-camphoric acid, Hnta = nicotinic acid and DL-Hcam = monodehydrated dl-camphoric acid), have been synthesized under hydrothermal conditions. Complex 1 is a three-dimensional hydrogen bonding framework composed of two kinds of 1D helical chains which exhibit the same right-handed helix, whereas complex 2 is constructed with one kind of 1D racemic chains. Interestingly, both two chiral molecules in the structures play important roles in the absolute helicity although they are not in the backbones of the helix which are made of rigid achiral ligands. Furthermore, different coordination modes of chiral ligands regulated the fluorescent emission.