Supramolecular structures of Ni(II) and Pt(II) based on the substituted 2, 2′: 6′, 2″-terpyridine: Synthesis, structural characterization, luminescence and thermal properties
Graphical abstract
Introduction
The coordination chemistry of 2,2′:6′,2″-terpyridine (tpy) and its derivatives has experienced a rapid expansion in the past decades in a wide range of applications such as supramolecular chemistry, antitumor activity, DNA intercalation, luminescent devices and catalysis [1], [2], [3], [4], [5], [6], [7], [8], [9], [10]. Most of the 4′-substituted derivatives of the tridentate terpyridine complexes are in [M(tpy)]n+ or [M(tpy)2]m+ forms which almost depends upon the central metal atom; however, the role of the substituent at the 4′-position of the terpyridine should be considered on the coordination number of metal [1], [7], [11]. The π-π stacking interactions in 4′-phenyl-2,2′:6′,2″-terpyridine derivatives of Mn, Fe, Co and Cu can control the self-assembly of these complexes [11]. Two excellent ligands for the design of supramolecular polymers self-assembled from a terpyridine ligand are functionalized ligand in the 4′-position with a hydroxyl group or a heterocycle, e.g. 4-pyridine [12], [13], [14], [15], [16]. Terpyridines were also found to form stable square-planar or octahedral complexes with d8 late transition metal ions such as Ni(II) and Pt(II) [13], [17], [18], [19], [20], [21]. There are several synthetic methods for the preparation of the terpyridine derivatives of platinum(II) which are involved [PtCl2(COD)] (COD = 1,5-cyclooctadiene), K2PtCl4, cis/trans-[PtCl2(SMe2)2], cis-[PtCl2(NCPh)2] or cis-[PtCl2(DMSO)2] [17]. The first example of the preparation of the Pt(II)-tpy complex has been reported in 1934 by Morgan et al. who described that the reaction of K2PtCl4 and terpyridine in H2O affords [Pt(tpy)Cl]Cl. 3H2O as a minor product as well as the double salt [Pt(tpy)Cl]2[PtCl4] as a major product [22].
Interestingly, the diimine and terpyridine complexes of platinum(II) reveal Pt…Pt and π-π interactions, resulting in the formation of the red and yellow polymorphs of platinum which would change the electronic properties of these complexes [23], [24], [25]. The linear chain platinum(II) complexes reveal the interesting spectroscopic properties due to the intermolecular stacking interactions [23]. However, a few linear chain platinum(II)-terpyridine complexes have been structurally characterized [25], [26], [27]. Two different stacking arrangements in the red and yellow forms of [Pt(tpyCl)Cl] depend on the solvent of crystallization. Therefore, the energy difference between these two structures is very small. The red form reveals Pt…Pt interaction in a linear chain but the yellow form exhibits only pairwise short Pt…Pt [25]. The identification of platinum-platinum interaction is easily achieved by structural characterization via single X-ray diffraction. However, indirect evidence of these interactions can be obtained using luminescence properties [28], [29], [30], [31]. It has been shown that the terpyridine complexes of platinum are able to be chromogenic and luminescent sensors for acids and bases [32], [33]. 4′-substituted terpyridines have been described in which 4′-substitution plays an important role in the structure determination. The role of metal center, anion and solvent should be considered in the crystal engineering design [34]. Note that the M-Cl moieties are among the good hydrogen bond acceptors, forming hydrogen bonds containing OH or NH fragments [35], [36]. Taking into account all of these information, we report the preparation and characterization of three new Ni(II) and Pt(II) complexes derived from 4′-substituted terpyridine ligands. In addition, the thermal and luminescence behaviors of these complexes were investigated.
Section snippets
General remarks
Elemental analyses were performed by Thermo Finnigan Flash Ea 111 elemental analyzer. IR spectra in the 4000-400 cm−1 were recorded on KBr pellets using ABB Bomem Model FTLA200-100 spectrophotometer. The luminescence study was performed using a Perkin-Elmer LS50 luminescence spectrometer. Experiments were carried out at room temperature. The excitation and emission band pass (slit) was 10 nm with the scan rate of 1000 nm/min. The solutions were placed in a 1 cm path-length quartz cell for the
Synthesis and structure of the nickel complex
The red single crystals of complex [Ni(pytpy)2]Cl2. H2O (1) were prepared by the reaction of NiCl2·6H2O and pytpy in 1:2 M ratio in water under hydrothermal conditions as shown in Scheme 1. We could obtain suitable single crystals only under hydrothermal conditions. The resulting product under normal conditions were not soluble in most of organic solvents. Therefore, we could not prepare suitable single crystals under normal conditions. The complex 1 is air stable which was characterized by IR,
Conclusions
In conclusion, the substituted terpyridine ligands of 4′-(4-pyridyl)-2,2′:6′,2″-terpyridine) and 4′-hydroxy-2,2′:6′,2″-terpyridine are among the most suitable ligands for the construction of supramolecular chemistry. Easy synthetic access of all of the reported compounds opens new possibilities for the design of different types of 4′-functionalized terpyridine as building blocks in supramolecular chemistry. Two substituted terpyridine complexes of Ni(II) and Pt(II) gave single crystals suitable
Acknowledgements
We would like to thank the Iran National Science Foundation (INSF) for financial support (Grant No. 93051215). We also thank the Science Research Council of K.N. Toosi University of Technology for financial support.
References (42)
- et al.
Synthesis and luminescence properties of platinum(II) complexes of 4′-chloro-2,2′:6′,2′′-terpyridine and 4,4′,4′′-trichloro-2,2′:6′,2′′-terpyridine
Inorg. Chim. Acta
(2001) - et al.
Synthesis, structure and characterization of metal complexes containing 4′-phenyl-2,2′:6′,2′′-terpyridine ligands with extended π… π interactions
Inorg. Chim. Acta
(2013) - et al.
Expanding the 4,4′-bipyridine ligand: structural variation in {M(pytpy)2}2+ complexes (pytpy = 4′-(4-pyridyl)-2,2′:6′,2′′-terpyridine, M = Fe, Ni, Ru) and assembly of the hydrogen-bonded, one-dimensional polymer {Ru(pytpy)(Hpytpy)}n3n+
Inorg. Chim. Acta
(2008) Platinum complexes of terpyridine: synthesis, structure and reactivity
Coord. Chem. Rev.
(2009)- et al.
Luminescence that lasts from [Pt(trpy)X]+ derivatives (trpy= 2,2′:6′,2′′-terpyridine)
Coord. Chem. Rev.
(2002) - et al.
Metal-metal stacking patterns between and with [Pt(tpy)X]+ cations
Inorg. Chim. Acta
(2010) - et al.
Design of novel copper(II) and zinc(II) coordination polymers based on the 4'-functionalized terpyridines
Polyhedron
(2015) - et al.
Synthesis and photophysical properties for fluorescent hexameric metallomacrocycles: zinc(II)-mediated self-assembly of bis(terpyridine) ligands
Inorg. Chim. Acta
(2007) 2,2′:6′,2′′-Terpyridines: from chemical obscurity to common supramolecular motifs
Chem. Soc. Rev.
(2007)- et al.
Recent developments in the supramolecular chemistry of terpyridine-metal complexes
Coord. Soc. Rev.
(2004)
New 4′-functionalized 2,2′:6′,2′′-terpyridines for applications in macromolecular chemistry and nanoscience
Eur. J. Org. Chem.
Square-planar Pd(II), Pt(II), and Au(III) terpyridine complexes: their syntheses, physical properties, supramolecular constructs, and biomedical activities
Chem. Rev.
A general and highly efficient protocol for the synthesis of chalcogenoacetylenes by copper(I)-terpyridine catalyst
SYNLETT
Design of coordination polymers with 4′-substituted functionalized terpyridyls in the backbone and pendent cyclopentadienyliron moieties
Polym. Chem.
Synthesis, characterization and cytotoxicity of Pt(II), Pd(II), Cu(II) and Zn(II) complexes with 4′-substitute terpyridine
Appl. Organomet. Chem.
Cytotoxicity of 2,2′:6′,2′′-terpyridineplatinum(II) complexes against human ovarian carcinoma
J. Med. Chem.
Electronic spectroscopy of chloro(terpyridine)platinum(II)
Inorg. Chem.
4′-(Pyridyl)-2,2′:6′,2′′-terpyridine ligands: discrete metal complexes and their polymeric assemblies as a function of N- pyridyl substitution patterns
Supramol. Chem.
Isolation and structure of a hydrogen-bonded 2,2′:6′,2′′-terpyridine- 4′-one acetic acid adduct
Aust. J. Chem.
The first example of a coordination polymer from the expanded 4,4′-bipyridine ligand [Ru(pytpy)2]2+ (pytpy = 4′-(4-pyridyl)-2,2′:6′,2′′-terpyridine)
CrystEngComm
A one dimensional copper(II) coordination polymer containing [Fe(pytpy)2]2+ (pytpy = 4′-(4-pyridyl)-2,2′:6′,2′′-terpyridine) as an expanded 4,4′-bipyridine ligand: a hydrogen-bonded penetrated by rod-like polymers
CrystEngComm
Cited by (14)
Progress in design and applications of supramolecular assembly of 2,2′:6′,2″-terpyridine-based first row d-block elements
2024, Coordination Chemistry ReviewsJahn-Teller distortion in bis(terpyridine)nickel(III) – Elongation or compression?
2023, Results in ChemistryRecent advances in the design and applications of platinum-based supramolecular architectures and macromolecules
2023, Coordination Chemistry ReviewsPenta-coordinated Cr(II) and Cu(II) complexes appended with 4′-(4-quinolyl)-2,2′:6′,2″-terpyridine: Crystal structure, Hirshfeld surface analysis, luminescence and thermal properties
2023, Journal of Molecular StructureCitation Excerpt :4′-Substituted-2,2′:6′,2″-terpyridine (tpy) ligands as a tridentate pincer ligand are among the modern N-heterocycles with a unique structure because of their excellent complexing ability towards various metal ions including main group, transition metals, lanthanides and actinides [1–6]. These ligands are of particular interest in catalysis and nanomaterials and are good candidates for the formation of coordination polymers and supramolecules [7–16]. Strikingly, terpyridine complexes are known for their broad biological activities; anticancer potency, antibacterial and antiproliferative properties are the most extensively studied [17–23].
The effect of 2-, 3- and 4-pyridyl substituents on photophysics of fac-[ReCl(CO) <inf>3</inf> (n-pytpy-κ <sup>2</sup> N)] complexes: Experimental and theoretical insights
2019, Journal of LuminescenceCitation Excerpt :2,2′:6′,2′′-Terpyridine (terpy) and 4′-functionalized terpy derivatives (4′-R-terpy) form remarkable organic building blocks for coordination and supramolecular chemistry [1,2].
Heteroleptic complexes of silver(I) featuring 4′-hydroxy- and 4′-(2-furyl)-2, 2′:6′ 2″-terpyridine: An easy route for synthesis of silver nanoparticles
2019, Inorganica Chimica ActaCitation Excerpt :Terpyridines act as hypodentate ligands and coordinate as mono-, bi- or tridentate ligands even in the same structure, although they are rare [11,12]. Terpyridine complexes with a range of metals have been reported such as Sn, Mn, Fe, Co, Ni, Cu, Zn, Ru, Cd [13–18]. Among them, late and large transition metals such as Pt(II) and Ag(I) ions, d8 and d10 electronic configurations, are of particular interest because they have NMR active spin 1/2 nuclei that can be used for providing more insight in solution state [19–22].