Research paperSynthesis, structure and photoluminescence properties of {Zn2Ln2} heterometallic complexes with anions of 1-naphthylacetic acid and N-donor heterocyclic ligands
Graphical abstract
Introduction
One of the most actively developing trends of the modern chemistry and material science is the design of dynamic molecular crystals with tunable physical properties [1]. Intra- and intermolecular interactions allowing effective transfer of the external energy along the chain of molecules involved into π-stacking are important tools in the engineering of such crystal systems. It was shown that variation of π-conjugation degree can be utilized for fine tuning of the electrical conductivity in organic conductors [2]. The ordered arrangement of the layers of redox-active aromatic molecules permits realizing reversible stepwise redox transformations leading to the selective formation of conductive organic networks in the single crystals [3]. Moreover, it has been revealed that the targeted organization of highly efficient π-stacking interactions in luminescent coordination compounds of single crystals of the rare-earth elements leads to the significant increase of the energy transfer efficiency along the conjugation chain at the distance up to 300 nm [4], and to the essential increase of the external quantum yield of luminescence [5]. These results stimulate further investigation of the role of intermolecular interactions (dipole-dipole, stacking, etc) in crystals on the energy transfer efficiency from ligand antennas to the lanthanide ion.
In this work we focused on the crystals of tetranuclear molecules with Zn2Ln2 metal core containing bridging anions of 1-naphthylacetic acid. It is notable that unlike the anions of 1-naphthoic acid, which were used by us recently for the synthesis of the photoactive {ZnEu}-complexes series [5], the anion of 1-naphthylacetic acid (Hnaphac) has a CH2-spacer, which can formally “block” an effective energy transfer from the naphthyl group to the lanthanide ion [6]. However, at the same time the CH2-spacer provides higher solubility of the reaction products in organic solvents what allowed us to expand substantially the family of ZnLn-coordination compounds and to investigate in detail the influence of the targeted chemical modification of the ligand environment on the possibility of directed formation of effective π-stacking interactions, and also to estimate the result of thus effects on the composition of the molecular metal core.
Section snippets
Synthesis
All operations related to synthesis of new complexes were conducted in air using commercially available solvents (ethanol (96%, FEREYN), acetonitrile (CP, CHIMMED)), and reagents (4,4′-dimethyl-2,2′-bipyridine (AcrosOrganics, 99%+); 4,4′-di-tert-butyl-2,2′-bipyridine (ALDRICH, 98%); pyridine (CarlRothGmbh + CoKG, 99%+); 1-naphthylacetic acid (AcrosOrganics, 95%); KOH (PFA, CHIMMED); Zn(NO3)2·6H2O (P, CHIMMED); Eu(NO3)3·6H2O (99.95%), Tb(NO3)3·6H2O (99.99%), Nd(NO3)3·6H2O (99%+), Gd(NO3)3·6H2O
Synthesis
The synthesis of new {Zn2Ln2}-complexes was conducted through the metathesis of inorganic metal salts, potassium salt of 1-naphthylacetic acid (Knaphac), and also by substitution of the pivalic acid anions in the trinuclear complex [Zn2Eu(NO3)(Piv)6(MeCN)2] with anions of 1-naphthylacetic acid, both processes being performed in the presence of the corresponding N-donor ligand. In the latter case the substitution of carboxylate anions in presence of 4,4′-dimethyl-2,2′-bipyridine
Conclusions
Thus within we have proposed and successfully utilized two approaches for synthesis of new {Zn2Ln2} heterometallic complexes with 1-naphthylacetic anions, namely: the substitution of Piv− to naphac− in [Zn2Eu(NO3)(Piv)6(MeCN)2] which takes place with the reorganization of the {Zn2Eu} metal core to {Zn2Eu2} one; the exchange reaction of Knaphac with zinc(II) and 4f-metals nitrates, – both processes happen in the presence of N-donor ligands. Through exchange reactions it was possible to isolate
Acknowledgments
This research was financially supported by the Russian Science Foundation (project 14-23-00176, (compounds 1 and 4) and 16-13-10537 (compounds 2, 3, 5 - 10)). This work was partially performed using the equipment of the Joint Research Centre of Kurnakov Institute of General and Inorganic Chemistry and Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences.
References (16)
- et al.
J. Kankare
(1997) Nat. Chem.
(2016)- et al.
Nat. Chem.
(2016) - et al.
J. Am. Chem. Soc.
(2016) - et al.
Inorg. Chem.
(2015) - et al.
Chem. Asian J.
(2016) - et al.
J. Appl. Spectrosc.
(2007) - et al.
Russ. Chem. Bull.
(2013)
Cited by (26)
Mono- and binuclear Cu (II) 3,5-diiodosalicylates: Structures and features of non-covalent interactions in crystalline state
2021, Journal of Molecular StructureCitation Excerpt :Carboxylate complexes represent one of the most intensively studied classes of coordination compounds[1-9].
Cu(II) 2-iodobenzoates: precursor-dependent formation of paddlewheel-like [Cu<inf>2</inf>(OOCR)<inf>4</inf>L<inf>2</inf>] or [Cu<inf>2</inf>L<inf>4</inf>(OOCR)<inf>2</inf>Cl<inf>2</inf>] binuclear complexes
2021, Inorganica Chimica ActaCitation Excerpt :Carboxylate complexes belong to the best-represented and, probably, best-studied class of coordination compounds, demonstrating remarkable structural diversity[1–10] and numerous useful physical features making them applicable in materials science.[11–18]
Magnetic properties and crystal structures of two copper coordination compounds with pentafluorobenzoate ligand
2021, Inorganica Chimica ActaCitation Excerpt :Several effective synthetic strategies have been employed to construct coordination compounds in the past several decades [10–16]. The most useful strategy to construct such compounds is to employ suitable organic ligand, for example, carboxylic acid is a versatile ligand for forming diverse coordination compounds owing to the oxygen atoms binding to metal centers by various coordination modes [17–23]. Moreover, the carboxylate ligand plays an important role in the magnetic exchange pathways between paramagnetic centers and shows various magnetic interactions.
Simple synthetic protocol to obtain 3d-4f-heterometallic carboxylate complexes of N-heterocyclic carbenes
2020, Inorganica Chimica ActaHalogen bonding in heteroleptic Cu(II) 2-iodobenzoates
2019, PolyhedronCitation Excerpt :Among the most widespread organic or inorganic XB-compatible building blocks, there are halogenated alkanes (especially iodoform and diiodomethane) [9–13], polyhalides [14–22], iodoarenes [23–27] etc, and this palette is still to be expanded. Carboxylates represent one of the most numerous classes of coordination compounds [28–37]. Surprisingly, although halogenated benzoic acids are easily available, and numerous complexes with halocarboxylates were reported [38–43], their potential as XB donors seems to be yet underestimated.
Mononuclear dysprosium complex with single-ion magnetic behavior and its highly selective detection of 1,4-dioxane
2019, PolyhedronCitation Excerpt :Lanthanide complexes are widely used in many fields. Because of their special electron arrangement, lanthanide complexes have good luminescence and magnetic properties [1], such as high density information storage, quantum computation, light-emitting diodes, bioluminescence labeling and environmental detection have shown great potential applications [2–6]. However, the properties of these complexes in solution state are very important for environmental detection, and mass spectrometry is an important basis for the detection of their behavior in solution state.