Functionalization and further crosslinking of the nicalon polycarbosilane based on its metalation with the n-butyllithium—postassium t-butoxide reagent

Reaction of the Nicalon polycarbosilane with the n-BuLi/Me₃COK reagent resulted in metalation of approximately one CH₂ group in four. Reaction of the metalated polymer with Me₂ (CH₂ = CH)SiCl gave a Me₂(CH₂ = CH)Si-substitued Nicalon polycarbosilane. The polymer was heated with different amounts of the [(MeSiH)_～0.8(MeSi)_～0.2]_n polysilane in the presence of azobisisobutyronitrile in refluxing benezene. Hydrosilylation by the Si? H-containing polysilane of the CH₂?CH groups of the Me₂(CH₂?CH) Si-substituted Nicalon polycarbosilane gave a new hybrid polymer (when appropriate quantities of reactant polymers were used) whose pyrolyis in a stream of argon to 1000°C left a ceramic residue in 77% yield whose elemental analysis indicated a nominal composition of 91% by weight SiC and 9% C.     

螺桨烷型分子BX[(CH_2)_n]_3和BX(CH_2)[CH(CH_2)_nCH](X=N,P)的结构和性质

采用密度泛函理论(DFT)研究了螺桨烷型分子BX[(CH2)n]3和BX(CH2)[CH(CH2)n CH](X=N,P;n=1-6)的结构、稳定性、化学键和电子光谱性质.计算结果表明这些分子都是稳定的.BX[(CH2)n]3(X=N,P;n=1-6)的最高占据分子轨道(HOMO)和最低空分子轨道(LUMO)之间的能隙均大于5.20 eV,其中BN[CH2]3和BP[CH2]3的能隙超过7.0 eV,与C5H6的能隙(7.27 eV)很接近,BX(CH2)[CH(CH2)n CH](X=N,P;n=1-6)的能隙在6.80 eV左右.所研究分子能量的二阶差分表明BN[(CH2)3]3、BP[(CH2)4]3及BX(CH2)[CH(CH2)2CH](X=N,P)是最稳定的.BX[(CH2)n]3的Wiberg键级表明除了BN[(CH2)n]3(n=2和6)中不存在B―N键,其它化合物中B和N均形成了化学键,BP[(CH2)n]3中除了BP[(CH2)2]3不存在B―P键,其它的均存在.电子密度的拓扑分析表明N―B键属于离子键,而P―B键具有共价键特征.BX[(CH2)n]3(X=N,P)的第一垂直激发能分别在191.1-284.8 nm和191.8-270.1 nm之间,BX(CH2)[CH(CH2)n CH](X=N,P)的第一垂直激发能分别在190.5-199.7 nm和209.0-221.3 nm之间.     

Reaction of N‐Heterocyclic Silylenes with Thioketone: Formation of Silicon–Sulfur Three (Si‐C‐S)‐ and Five (Si‐C‐C‐C‐S)‐Membered Ring Systems

Three‐ and five‐membered rings that bear the (Si‐C‐S ) and (Si‐C‐C‐C‐S ) unit have been synthesized by the reactions of L SiCl ( 1 ; L =PhC(NtBu)₂) and L′ Si ( 2 ; L′ =CH{(C?CH₂)(CMe)(2,6‐iPr₂C₆H₃N)₂}) with the thioketone 4,4′‐bis(dimethylamino)thiobenzophenone. Treatment of 4,4′‐bis(dimethylamino)thiobenzophenone with L SiCl at room temperature furnished the [1+2]‐cycloaddition product silathiacyclopropane 3 . However, reaction of 4,4′‐bis(dimethylamino)thiobenzophenone with L′ Si at low temperature afforded a [1+4]‐cycloaddition to yield the five‐membered ring product 4 . Compounds 3 and 4 were characterized by NMR spectroscopy, EIMS, and elemental analysis. The molecular structures of 3 and 4 were unambiguously established by single‐crystal X‐ray structural analysis. The room‐temperature reaction of 4,4′‐bis(dimethylamino)thiobenzophenone with L′ Si resulted in products 4 and 5 , in which 4 is the dearomatized product and 5 is formed under the 1,3‐migration of a hydrogen atom from the aromatic phenyl ring to the carbon atom of the C? S unit. Furthermore, the optimized structures of probable products were investigated by using DFT calculations.     

Kinetic parameters of the cyclization and decyclization reactions of nitrogen- and oxygen-containing radicals

The intersecting parabolas model is used to analyze experimental data for the following radical cyclization and decyclization reactions: RCH=CH(CH₂)_nN·R₁ cyclo-[NR₁CH(CH₂)_n]C·HR,R(CH₂)₂OOCH₂C·HR cyclo-[RCHOCH₂] + RCH₂CH₂O·, cyclo-[(CH₂)_nOOCHC· HR] cyclo-[RCHOCH](CH₂)_nO·, cyclo-[(CH₂)_nOC·RO] RC(O)O(CH₂) _n–1C·H₂, and cyclo-[(CH₂)_nCHO·] CH(O)(CH₂) _n–1C·H₂. The activation energy of the thermally neutral reaction (E _e,0) is calculated for each class of reactions. E _e,0 depends on the electronegativity of the heteroatom Y of the reaction center C C...Y, the force constants of the reacting bonds, and the strain energy of the ring formed. For the cyclization and decyclization of six-membered rings, the empirical relationship between the elongation of the reacting bonds in the transition state (r _e) and the difference in electronegativity (EA) between the C and Y atoms (Y = C, N, O) has the form r _e ×10₁₁, m = 3.83 – 0.0198(EA, kJ/mol).Translated from Kinetika i Kataliz, Vol. 46, No. 1, 2005, pp. 5–13.Original Russian Text Copyright © 2005 by Denisova, Denisov.     

Intermediates in the reactions of electron-rich germylenes with an acyl azide: An MNDO-SCF-MO investigation

The experimentally known reaction between the electron-rich germylene [(Me₃Si)₂N]₂Ge andp-CH₃C₆H₄SO₂N₃ has been modeled computationally by MNDO calculations on the reaction intermediates formed by [CH₃Si)₂E]₂Ge (E=N or CH) and CH₃CON₃. Molecular and electronic structures have been established for the acyclic germaketimines [(CH₃Si)₂E]₂Ge=N-N=N-COCH₃ (the primary 11 adducts formed by the reactants) and [CCH₃Si)₂E]₂Ge=N-COCH₃, and for the cyclic species [(H₃Si)₂E]₂Ge-N=N-N=C(CH₃)-O, [(H₃Si)₂E]₂Ge-N=N-N(COCH₃), and [(H₃Si)₂E]₂-Ge-N=C(CH₃-O. The intermediates [(H₃Si)₂E]₂-GeN(N₂)COCH₃ were found, upon formation, to undergo smooth dissociation along the N()-N() bond, with loss of N₂, to provide acyclic [H₃Si)₂E]₂Ge=N-COCH₃; the polymerizations of these latter species to form polygermazanes are extremely exothermic.     

Silicon‐terminated telechelic oligomers by ADMET chemistry: Synthesis and copolymerization

Methoxydimethylsilane and chlorodimethylsilane‐terminated telechelic polyoctenomer oligomers (POCT) have been prepared by acyclic diene metathesis (ADMET) chemistry using Grubbs' ruthenium Ru(Cl₂)(CHPh)(PCy₃)₂ [Ru] or Schrock's molybdenum Mo(CH CMe₂Ph)(N 2,6 C₆H₃ i Pr₂)(OCMe(CF₃)₂)₂ [Mo] catalysts. These macromolecules have been characterized by FTIR, ¹H‐, ¹³C‐, and ²⁹Si‐NMR spectroscopy. The molecular weight distributions of these polymers have been determined by GPC and vapor pressure osmometry (VPO). The number‐average molecular weight (M_n) values of the telechelomers are dictated by the initial ratio of the monomer to the chain limiter. The termini of these oligomers (M_n = 2000) can undergo a condensation reaction with hydroxy‐terminated poly(dimethylsiloxane) (PDMS) macromonomer (M_n = 3300) [HO Si(CH₃)₂ O { Si(CH₃)₂O }_x  Si(CH₃)₃], producing an ABA‐type block copolymer, as follows: (CH₃)₃SiO [ Si(CH₃)₂O ]_x [ CHCH (CH₂)₆ ]_y [ OSi(CH₃)₂ ]_x OSi(CH₃)₃. The block copolymers were characterized by ¹H‐ and ¹³C‐NMR spectroscopy, VPO, and GPC, as well as elemental analysis, and were determined by VPO to have a M_n of 8600. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 849–856, 1999     

Mass spectra of some neopentylphosphorus derivatives

The fragmentation patterns and major metastable ions of the mass spectra of the neopentyl-phosphorus derivatives [(CH₃)₃CCH₂]₃P, [(CH₃)₃CCH₂]₂P(O)H, [(CH₃)₃CCH₂]_nPX_3-n (n = 1 and 2; X = H, Cl, C₆H₅ and CH = CH₂), [(CH₃)₃CCH₂]₃PS, [(CH₃)₃CCH₂]_nP(S)R_3-n (n = 1 and 2; R = C₆H₅ and CH = CH₂), [(CH₃)₃ CCH₂]₂PCH₂CH₂P[CH₂C(CH₃)₃]₂, ([CH₃)₃CCH₂]₂PCH₂PCH₂-CH₂P(H)C₆H₅ and [(CH₃)₃CCH₂]₂PCH₂CH₂P(S)(CH₃)₂ are described. Fragmentation of a neopentyl group by elimination of either C₄H₈ or CH₃ is very favourable when the neopentyl group is bonded to either a tricoordinate or tetracoordinate phosphorus atom. In neopentylphosphines with two or three neopentyl groups, stepwise elimination of C₄H₈ from all of the neopentyl groups occurs very readily. The resulting [(CH₃)_nPX]^+._3-n ions are often the most intense ions in the mass spectra.     

Metal-containing initiator systems. V. Radical and cationic polymerizations with initiator systems of reduced nickel and chlorosilanes

The polymerizations of methyl methacrylate, styrene, and isobutyl vinyl ether with the binary systems of reduced nickel and chlorosilanes [(CH₃)_nSiCl_4?n, n = 0–3] have been investigated. It was found that these systems could act as both radical and cationic initiators, depending on the nature of vinyl monomers used. The kinetic investigations indicated that methyl methacrylate polymerized via a radical mechanism, and the initiating activity of chlorosilanes decreased in the following order: SiCl₄ > CH₃SiCl₃ > (CH₃)₂SiCl₂ > (CH₃)₃SiCl ? 0. Cationic initiations were observed in the polymerizations of styrene and isobutyl vinyl ether. In the latter case, the activity of chlorosilanes was in the following order: (CH₃)₃SiCl > (CH₃)₂SiCl₂ > CH₃SiCl₃ ? SiCl₄. From the results obtained, a possible mechanism of selective initiation with these systems is proposed and discussed.     

Electrophilic Cyclization of Dimethyl(ω-phenylaminoalkyl)alkenylsilanes

Unsaturated organosilicon amines [CH₂ = CH(CH₂) _n ]Me₂Si[(CH₂) _m NHPh] at the action of Hg(OAc)₂ in THF solution transform to corresponding heterocycles. Regioselectivity of this intramolecular electrophilic heterocyclization is defined by the position of double bond relatively to the silicon atom. This is caused by -effect of the silyl group.     

Reaction of lanthanide(II) and lanthanide(III) phenylethynyl cuprates with acetyl chloride

Praseodymium and ytterbium phenylethynyl cuprates [(PhC≡C)₃Cu]₃Pr₂(THF)₆ and {[(PhC≡C)₃Cu]·Yb(THF)₂}₂ react with acetyl chloride in tetrahydrofuran with elimination of phenylethynylcopper and formation of alkoxides [PhC≡C-CCl(CH₃)O] _n Ln (n = 3, Ln = Pr; n = 2, Ln = Yb). Then praseodymium alkoxide forms ester [methyl (phenylethynyl)chloromethylethanoate] and praseodymium chloride, alkoxy derivative. Itterbium alkoxide is oxidized to unsymmetrical dialkoxyitterbium chloride PhC≡C-CH(CH₃)-O-Yb(Cl)-O-CCl(CH₃)C≡CPh·2THF.     

Influence of the size of the formed cycle on the reactivity of free radicals in cyclization reactions

Numerous experimental data for the cyclization of free radicals C·H₂(CH₂)_nCH=CH₂ cyclo-[(CH₂)_n+1CH(C·H₂)], and C·H₂(CH₂)_nCH=CHR cyclo-[(CH₂)_n+1C·HCHR] were analyzed in the framework of the parabolic model. The activation energy of thermoneutral (H _e = 0) cyclization E _e0 decreases linearly with an increase in the energy of cycle strain E _rsc: E _e0(n) (kJ mol–1) = 85.5 – 0.44E _rsc(n) (n is the number of atoms in the cycle). The activation entropy of cyclization S ^# also depends on the cycle size: the larger the cycle, the lower S ^#. A linear dependence of S ^# on the difference between the entropies of formation S° of cyclic hydrocarbon and the corresponding paraffin was found: S ^# = 1.00[S°(cycle) – S°(C_nH_2n+2)]. The E _e0 values coincide for cyclization reactions with the formation of the six-membered cycle and the bimolecular addition of alkyl radicals to olefins.     

Synthesis of Mixed-ring Zirconocene Complexes Containing Alkenyl Group and Ethylene Polymerization Catalyzed with Them

Four new mixed‐ring zirconium completes, [CH₂ = CH(CH₂)_n ‐C₅H₄](RC₅H₄)ZrCl₂ [n = l, R = CH₃OCH₂CH₂(3); n = 2, R = CH₃OCH₂CH₂ (4); n = 2, R=Me₃Si (5); n = 2, R = allyl (6)], have been prepared by the reaction of CH₂ = CH(CH₂)_n C₅H₄ZrCl₃, DME[n = l (1); n = 2 (2)] with RC₅H₄Li. When activated with methylaluminoxane (MAO), the catalytic activities of the above complexes in ethylene polymerization were tested. Complexes 5 and 6 show high activities similar to Cp₂ZrCl₂. Introduction of methoxyethyl group into Cp‐ligand dramatically decreases the catalytic activities of complexes 3 and 4, which can be overcome by increasing the amount of MAO. For complex 5, the dependence of activity and molecular weight (Mη) on the Al/Zr ratio, the polymerization time (t_P), polymerization temperature (T_P) and the polymerization solvent volume (V) was investigated.     

Silicon‐ and Tin‐Containing Open‐Chain and Eight‐Membered‐Ring Compounds as Bicentric Lewis Acids toward Anions

Herein, we report the syntheses of silicon‐ and tin‐containing open‐chain and eight‐membered‐ring compounds Me₂Si(CH₂SnMe₂X)₂ ( 2 , X=Me; 3 , X=Cl; 4 , X=F), CH₂(SnMe₂CH₂I)₂ ( 7 ), CH₂(SnMe₂CH₂Cl)₂ ( 8 ), cyclo‐Me₂Sn(CH₂SnMe₂CH₂)₂SiMe₂ ( 6 ), cyclo‐(Me₂SnCH₂)₄ ( 9 ), cyclo‐Me_(2?n)X_nSn(CH₂SiMe₂CH₂)₂SnX_nMe_(2?n) ( 5 , n=0; 10 , n = 1, X= Cl; 11 , n=1, X= F; 12 , n=2, X= Cl), and the chloride and fluoride complexes NEt₄[cyclo‐ Me(Cl)Sn(CH₂SiMe₂CH₂)₂Sn(Cl)Me?F] ( 13 ), PPh₄[cyclo‐Me(Cl)Sn(CH₂SiMe₂CH₂)₂Sn(Cl)Me?Cl] ( 14 ), NEt₄[cyclo‐Me(F)Sn(CH₂SiMe₂CH₂)₂Sn(F)Me?F] ( 15 ), [NEt₄]₂[cyclo‐Cl₂Sn(CH₂SiMe₂CH₂)₂SnCl₂?2 Cl] ( 16 ), M[Me₂Si(CH₂Sn(Cl)Me₂)₂?Cl] ( 17 a , M=PPh₄; 17 b , M=NEt₄), NEt₄[Me₂Si(CH₂Sn(Cl)Me₂)₂?F] ( 18 ), NEt₄[Me₂Si(CH₂Sn(F)Me₂)₂?F] ( 19 ), and PPh₄[Me₂Si(CH₂Sn(Cl)Me₂)₂?Br] ( 20 ). The compounds were characterised by electrospray mass‐spectrometric, IR and ¹H, ¹³C, ¹⁹F, ²⁹Si, and ¹¹⁹Sn NMR spectroscopic analysis, and, except for 15 and 18 , single‐crystal X‐ray diffraction studies.     

The stable silylene Si[(NCH2Bu)2C6H4-1,2]: Reactions with Group 14 element halides

Reaction of the thermally stable silylene Si[(NCH₂Bu^t)₂C₆H₄-1,2] (1) [abbrev. as Si(NN)] with SiX₄ (X = Cl or Br) afforded the disilanes (NN)SiX(SiX₃) and [(NN)SiX]₂ (X = Br only), the trisilane (NN)SiX-[(SiX₃)Si(NN)] and the monosilane (NN)SiX₂ (X = Br only), whereas treatment of 1 with MCl₄ (M = Ge or Sn) yielded (NN)SiCl₂ and MCl₂. [(NN)SiBr]₂ and (NN)SiBr₂ were also obtained by reaction of 1 with Br₂. Reaction of 1 with PhSiCl₃ yielded the disilane (NN)SiCl(SiCl₂Ph) and trisilane [(NN)SiCl]₂SiClPh, whereas the disilane (NN)SiCl(SiCl₂Me) was obtained with MeSiCl₃. The trisilane (NN)SiCl-[(SiCl₃)Si(NN)] was thermally labile and converted to [(NN)SiCl]₂SiCl₂.     

Spontaneous Double Hydrometallation Induced by N→M Coordination in Organometallic Hydrides of Group 14 Elements

Our attempts to synthesise N→M intramolecularly coordinated diorganometallic hydrides L₂MH₂ [M=Si ( 4 ), Ge ( 5 ), Sn ( 6 )] containing the CH=N imine group (in which L is C,N‐chelating ligand {2‐[(2,6‐iPr₂C₆H₃)N=CH]C₆H₄}^?) yielded 1,1′‐bis(2,6‐diisopropylphenyl)‐2,2′‐spriobi[benzo[c][1,2]azasilole] ( 7 ), 1,1′‐bis(2,6‐diisopropylphenyl)‐2,2′‐spriobi[benzo[c][1,2]azagermole] ( 8 ) and C,N‐chelated homoleptic stannylene L₂Sn ( 10 ), respectively. Compounds 7 and 8 are an outcome of a spontaneous double hydrometallation of the two CH=N imine moieties induced by N→M intramolecular coordination (M=Si, Ge) in the absence of any catalyst. In contrast, the diorganotin hydride L₂SnH₂ ( 6 ) is redox‐unstable and the reduction of the tin centre with the elimination of H₂ provided the C,N‐chelated homoleptic stannylene L₂Sn ( 10 ). Compounds 7 and 8 were characterised by NMR spectroscopy and X‐ray diffraction analysis. Because the proposed N→M intramolecularly coordinated diorganometallic hydrides L₂MH₂ [M=Si ( 4 ), Ge ( 5 ), Sn ( 6 )] revealed two different types of reduction reactions, DFT calculations were performed to gain an insight into the structures and bonding of the non‐isolable diorganometallic hydrides as well as the products of their subsequent reactions. Furthermore, the thermodynamic profiles of the different reaction pathways with respect to the central metal atom were also investigated.     

Germanium-carbon versus germanium-nitrogen double-bond formation in the reactions between germylenes and diazo compounds

The reactions between methyl diazoacetate, HC(N₂)COOMe, and a range of germylenes L₂Ge [L = CH₃], NH₂, OCH₃, Ph, CH=CH₂, SiH₃, (H₃Si)₂N, and (H₃Si)₂CH] have been studied using MNDO calculations. Molecular and electronic structures have been determined for the transoid germaketimines L₂Ge=N-N=C(H)COOMe [the primary 11 adducts of L₂Ge and HC(N₂)COOMe], for their cyclic cisoid isomers, and for the germaethenes L₂Ge=C(H)COOMe. The intermediate L₂GeCH(N₂)COOMe was found to dissociate smoothly along the unique GeC bond when L = NH₂, OCH₃, or (H₃Si)₂N (so leading to no net reaction) but to undergo facile loss of N₂, forming the germaethene L₂Ge=C(H)COOMe, when L = CH₃, Ph, CH=CH₂, SiH₃, or (H₃Si)₂CH. The calculations thus enable the prediction of substantially different patterns of reactivity, and hence different products, in the reactions between diazo compounds and the two closely similar germylenes [(Me₃Si)₂N]₂Ge and [(Me₃Si)₂CH]₂Ge.     

Bulky alkyls and amides of main group 5 elements II. Rotational barriers in phosphorus compounds containing bulky groups

The group [(CH₃)₃Si]₂CH is effectively bulkier than the (CH₃)₃C group in inhibiting rotation about the PC bond in R₂PCI compounds. In phosphonamidous chlorides, RP(CI)NR₂′, increasing the bulk of the groups at nitrogen, e.g., from CH₃ to (CH₃)₂CH to (CH₃)₃Si, increases the rotational barriers about the PN bond; however, changing R from (CH₃)₃C to [(CH₃)₃Si]₂CH increases the barrier, which is a reversal of the trend earlier observed. It is suggested that these very bulky silylated groups represent limiting cases of steric interference.     

An improved procedure for syntheses of silyl derivatives of the cubeoctameric silicate anion

The reaction of the Si₈O₂₀^8? silicate anion with X(CH₃)₂SiCl (X?H or CH₃) has been studied to develop a cost‐effective procedure for synthesizing Si₈O₂₀[Si(CH₃)₂X]₈ in high yield. Use of hexane as solvent and adjustment of the reaction temperature to ca 20 °C were found to be effective in promoting the reaction, by which Si₈O₂₀[Si(CH₃)₂X]₈ could be produced in good yield employing 24 mol of X(CH₃)₂SiCl per mole of Si₈O₂₀^8?. It was also demonstrated that the yield of Si₈O₂₀[Si(CH₃)₂X]₈ depends on the amount of solvent, suggesting that the amount is an important factor when scaling up the reaction to produce a large quantity of Si₈O₂₀[Si(CH₃)₂X]₈. Copyright © 2003 John Wiley & Sons, Ltd.     

Synthesis and reactivity of cyclopentadienyl ruthenium complexes containing ferrocenylselenolates

The heterotrimetallic complex 1,1′-[Fc(SeRuCp(PPh₃)₂)₂] is accessible by the reaction of 1,1′-[Fc(SeLi)₂·2THF] (Fc = Fe(η⁵-C₅H₄)₂, THF = Tetrahydrofuran) with two equivalents of CpRu(PPh₃)₂Cl in high yield. Complex 1,1′-[Fc(SeLi)₂·2THF] can be prepared by treatment of 1,1′-[Fc(SeSiMe₃)₂] with two equivalents of n-BuLi in THF solution. 1,1′-[Fc(SeRuCp(PPh₃)₂)₂] is converted to 1,1′-[Fc(SeRuCpCO(PPh₃))₂] under CO atmosphere in THF solution. The complexes 1,1′-[Fc(SeRuCp(PP))₂] [PP = Ph₂P(CH₂)PPh₂ (dppm), Ph₂P(CH₂)₂PPh₂ (dppe), Ph₂P(CH=CH)₂PPh₂ (dppee), Ph₂P(CH₂)₃PPh₂ (dppp)] are obtained in a one-pot reaction of CpRu(PPh₃)₂Cl and 1,1′-[Fc(SeLi)₂·2THF] with the chelating bisphosphine ligand.     

Novel organosilicon monomer for preparing transparent matrices doped with lanthanide complexes

Perfluoroadipic bis(trialkoxysilylpropyl)amide was synthesized as a mixture of five compounds with the general formula (EtO) _n (MeO)_3-n Si(CH₂)₃NHC(O)(CF₂)₄C(O)NH(CH₂)₃-Si(OMe) _n (OEt)_3-n (1, n = 1, 2). Hydrolysis of this product by a specified amount of water (1: 4) gave oligomers EtO[(HO)(EtO)Si(CH₂)₃NH(O)C(CF₂)₄C(O)NH(CH₂)₃Si(OEt)₂O]_nH ( _n = 7–9). From oligomer solutions, transparent glassy thermally stable films were obtained. The film material was studied by IR spectroscopy, atomic force microscopy, transmission electron microscopy, and powder X-ray diffraction. Compound 1 and oligomers can efficiently solvate lanthanide diketonate complexes. They displace water from the metal coordination sphere, and this water is then spent for hydrolysis of trialkoxysilyl groups. The luminescence intensity of matrix films based on the oligomers depends on the concentration of lanthanide complexes and is very low at 7n_exc = 330 nm, whereas the luminescence intensity of the Eu³⁺ cation is very high.