Design, Synthesis, and Anti-Cancer Evaluation of Novel Water-Soluble Copper(I) Complexes Bearing Terpyridine and PTA Ligands

This study presents a simple and energy-efficient self-assembly LAG synthetic method for novel water-soluble copper(I) complexes [Cu(terpy)(PTA)][PF6] (1) and [Cu(terpy)(PTA)2][PF6] (2). They were characterized by FT-IR, 1H, and 31P{1H} NMR spectroscopy, elemental analysis, and single-crystal/powder X-ray diffraction (for 2). The X-ray analysis of compound 2 indicates a bidentate coordination mode of terpyridine to the metal center. Variable-temperature NMR tests indicate dynamic properties for terpyridine in the case of both compounds, as well as for the PTA ligands in the case of 2. Additionally, compounds 1 and 2 exhibit interesting cytotoxic activity, which was tested on normal human dermal fibroblasts (NHDFs), human lung carcinoma (A549), human breast adenocarcinoma (MCF-7), and human cervix carcinoma (HeLa) established cell lines. In comparison to the other tested compounds, complexes 1 and 2 seem to have significantly lower IC50 values against cancer cells (A549, HeLa, MCF-7), indicating their potential as prospective anticancer agents. Moreover, both compounds show no significant toxicity towards normal skin cells (NHDFs), suggesting a certain selectivity in their action on cancer cells. Cisplatin as a reference compound also exhibited considerable cytotoxicity against cancer cells but with a low level of selectivity, which could lead to unwanted effects on normal cells. Remarkably, compounds 1 and 2 exhibit up to 30 times the cytotoxic activity of cisplatin, with a six-fold lower toxicity to normal cells. They also interact strongly with human serum albumin, suggesting potential therapeutic applications. Overall, these compounds hold significant promise as potential chemotherapeutic agents.

Modeling of the Response of Hydrogen Bond Properties on an External Electric Field: Geometry, NMR Chemical Shift, Spin-Spin Scalar Coupling

The response of the geometric and NMR properties of molecular systems to an external electric field has been studied theoretically in a wide field range. It has been shown that this adduct under field approach can be used to model the geometric and spectral changes experienced by molecular systems in polar media if the system in question has one and only one bond, the polarizability of which significantly exceeds the polarizability of other bonds. If this requirement is met, then it becomes possible to model even extreme cases, for example, proton dissociation in hydrogen halides. This requirement is fulfilled for many complexes with one hydrogen bond. For such complexes, this approach can be used to facilitate a detailed analysis of spectral changes associated with geometric changes in the hydrogen bond. For example, in hydrogen-bonded complexes of isocyanide C≡¹⁵N-¹H⋯X, ¹J(¹⁵N¹H) depends exclusively on the N-H distance, while δ(¹⁵N) is also slightly influenced by the nature of X.

Actual Symmetry of Symmetric Molecular Adducts in the Gas Phase, Solution and in the Solid State

This review discusses molecular adducts, whose composition allows a symmetric structure. Such adducts are popular model systems, as they are useful for analyzing the effect of structure on the property selected for study since they allow one to reduce the number of parameters. The main objectives of this discussion are to evaluate the influence of the surroundings on the symmetry of these adducts, steric hindrances within the adducts, competition between different noncovalent interactions responsible for stabilizing the adducts, and experimental methods that can be used to study the symmetry at different time scales. This review considers the following central binding units: hydrogen (proton), halogen (anion), metal (cation), water (hydrogen peroxide).

Orthogonal Coordination Chemistry of PTA toward Ru(II) and Zn(II) (PTA = 1,3,5-Triaza-7-phosphaadamantane) for the Construction of 1D and 2D Metal-Mediated Porphyrin Networks

This work demonstrates that PTA (1,3,5-triaza-7-phosphaadamantane) behaves as an orthogonal ligand between Ru(II) and Zn(II), since it selectively binds through the P atom to ruthenium and through one or more of the N atoms to zinc. This property of PTA was exploited for preparing the two monomeric porphyrin adducts with axially bound PTA, [Ru(TPP)(PTA-κP)₂] (1, TPP = meso-tetraphenylporphyrin) and [Zn(TPP)(PTA-κN)] (3). Next, we prepared a number of heterobimetallic Ru/Zn porphyrin polymeric networks—and two discrete molecular systems—mediated by P,N-bridging PTA in which either both metals reside inside a porphyrin core, or one metal belongs to a porphyrin, either Ru(TPP) or Zn(TPP), and the other to a complex or salt of the complementary metal (i.e., cis,cis,trans-[RuCl₂(CO)₂(PTA-κP)₂] (5), trans-[RuCl₂(PTA-κP)₄] (7), Zn(CH₃COO)₂, and ZnCl₂). The molecular compounds 1, 3, trans-[{RuCl₂(PTA-κ²P,N)₄}{Zn(TPP)}₄] (8), and [{Ru(TPP)(PTA-κP)(PTA-κ²P,N)}{ZnCl₂(OH₂)}] (11), as well as the polymeric species [{Ru(TPP)(PTA-κ²P,N)₂}{Zn(TPP)}]_∞ (4), cis,cis,trans-[{RuCl₂(CO)₂(PTA-κ²P,N)₂}{Zn(TPP)}]_∞ (6), trans-[{RuCl₂(PTA-κ²P,N)₄}{Zn(TPP)}₂]_∞ (9), and [{Ru(TPP)(PTA-κ³P,2N)₂}{Zn₉(CH₃COO)₁₆(CH₃OH)₂(OH)₂}]_∞ (10), were structurally characterized by single crystal X-ray diffraction. Compounds 4, 6, 9, and 10 are the first examples of solid-state porphyrin networks mediated by PTA. In 4, 6, 8, 9, and 11 the bridging PTA has the κ²P,N binding mode, whereas in the 2D polymeric layers of 10 it has the triple-bridging mode κ³P,2N. The large number of compounds with the six-coordinate Zn(TPP) (the three polymeric networks of 4, 6 and 9, out of five compounds) strongly suggests that the stereoelectronic features of PTA are particularly well-suited for this relatively rare type of coordination. Interestingly, the similar 1D polymeric chains 4 and 6 have different shapes (zigzag in 4 vs “Greek frame” in 6) because the {trans-Ru(PTA-κ²P,N)₂} fragment bridges two Zn(TPP) units with anti geometry in 4 and with syn geometry in 6. Orthogonal “Greek frame” 1D chains make the polymeric network of 9. Having firmly established the binding preferences of PTA toward Ru(II) and Zn(II), we are confident that in the future a variety of Ru/Zn solid-state networks can be produced by changing the nature of the partners. In particular, there are several inert Ru(II) compounds that feature two or more P-bonded PTA ligands that might be exploited as connectors of well-defined geometry for the rational design of solid-state networks with Zn–porphyrins (or other Zn compounds).

This work demonstrates, through the X-ray structural characterization of several polymeric Ru/Zn networks, that PTA (1,3,5-triaza-7-phosphaadamantane) behaves as an orthogonal ligand between Ru(II) and Zn(II). In fact, PTA selectively binds through the P atom to ruthenium and through one or more of the N atoms to zinc.

Investigating the reactivity of neutral water-soluble Ru(ii)–PTA carbonyls towards the model imine ligands pyridine and 2,2′-bipyridine

The reactivity of selected Ru(ii)-PTA carbonyls with potentially labile ligands (i.e. H₂O, dmso and/or Cl) towards the model imine ligands pyridine and 2,2′-bipyridine was investigated, yielding several neutral and cationic water-soluble derivatives.

Amberlite IR-120(H)-mediated “on water” synthesis of novel anticancer ruthenium(ii)–p-cymene 2-pyridinylbenzothiazole (BTZ), 2-pyridinylbenzoxazole (BOZ) & 2-pyridinylbenzimidazole (BIZ) scaffolds

A class of novel Ru(ii)–p-cymene BTZ, BOZ & BIZ complexes have been synthesized “on water” using Amberlite IR-120(H) resin and their anticancer activities were evaluated.