Diorganotin (IV) amino acid complexes as potential anticancer agents. Synthesis, structural characterization, and in vitro assays

Nine new organotin (IV) derivatives from L-amino acids (l-lysine, L-ornithine, L-glutamic acid, and L-aspartic acid) were synthesized by one-pot ultrasound-assisted methodology. All compounds were characterized by ATR-FTIR (Attenuated Total Reflectance-Fourier Transform Infrared), LRMS (Low-Resolution Mass Spectrometry), and solution NMR (1H, 13C, 119Sn Nuclear Magnetic Resonance) spectroscopies. Complexes Bu2Sn(Lys) (1), Ph2Sn(Lys) (2), Bu2Sn(Orn) (3), and Ph2Sn (Glu-OMe) (6a) were crystallized, and the structures were established by single-crystal X-ray diffraction analysis. Diffraction results evidenced that complexes 1 to 3 were five-coordinated mononuclear species while the phenyl substituted derivative Ph2Sn (Glu-OMe) (6a) forms a polymeric network via Sn-O-Sn bridging whereby the tin atom is six-coordinated. In turn, 119Sn NMR results revealed that all tin complexes exist as mononuclear penta-coordinated species in solution. The tin derivatives were screened for ADME (Adsorption, Distribution, Metabolism, and Excretion) properties via the freely available tools SWISS ADME, and the results were analyzed hereafter. The antiproliferative activity of the complexes was tested against three human cancer cell lines: colorectal adenocarcinoma HT-29, breast adenocarcinoma MDA-MB-231, and chondrosarcoma SW-1353 using a non-tumoral cell line of human osteoblast as control, demonstrating selective inhibitory activities against cancer cells. Hence, these compounds could be a promising alternative to classical chemotherapy agents.

Recent advancements of fluorescent tin(IV) complexes in biomedical molecular imaging

In the last few years, tin(IV) complexes have emerged as very attractive candidates in the field of molecular imaging due to their unique photophysical properties. Despite the few reviews published to date covering the chemistry of organotin and tin complexes and their cytotoxic potential, there are no reviews devoted to their live cell imaging properties. Therefore, this feature article summarizes the discussion of the fundamental photophysical properties of fluorescent tin metal complexes focusing on their recent advances in "biomedical molecular imaging". A debate on the design of tin complexes as cellular imaging agents relating to their chemical, electronic and photophysical properties is enclosed. This paper also discusses the imaging applications of tin complexes in cells, tissues, and organisms via confocal and multiphoton imaging for sensing mechanisms in cellular media, bioimaging, and therapeutic labeling. In addition, it explores and explains the current challenges and prospects associated with these tin complexes as emerging luminescent cellular agents for potential clinical use.

Engineered organotin(IV) and vanadium(V) derivatives with distinct coordination modes and luminescent properties for the efficient detection and quantification of permanganate ions

The distinction in coordination modes of metal complexes leads to their versatile structural features and unique properties. Here, we report two tetradentate Schiff base ligands (H₂L¹ and H₂L²) bearing N₂O₂ donor sets, tactically selected to provide distinct coordination modes with different metal ions. The ligands were utilized to synthesize their organotin(IV) (1-4) and vanadium(V) (5) derivatives. The synthesized compounds were characterized using elemental analysis, FT-IR spectroscopy, multi-nuclei NMR (¹H, ¹³C, and ¹¹⁹Sn) spectroscopy, mass spectrometry, and single-crystal X-ray diffraction. The organotin(IV) derivatives (1-4) displayed hepta-coordination around both the Sn centres as they were achieved in their dimeric form. Contrariwise, the vanadium(V) compound (5) was isolated as a mononuclear entity exhibiting penta-coordinated geometry around the vanadium centre. The variation in the coordination modes was evident in their UV-vis and fluorescence spectra. The organotin(IV) compounds (1-4) exhibited a strong emission band centred at 468 nm when excited at a wavelength of 360 nm whereas the vanadium(V) (5) derivative displayed poor fluorogenic response. Compound 1 was further explored for the fluorogenic chemo-sensing of permanganate ions (MnO₄^-) amongst various anions by quenching response. A detailed investigation of the recognition of permanganate ions was accomplished by spectrofluorometric, spectroscopic (¹¹⁹Sn NMR), mass spectrometric, and computational studies.

Multicomponent synthesis of chromophores – The one-pot approach to functional π-systems

Multicomponent reactions, conducted in a domino, sequential or consecutive fashion, have not only considerably enhanced synthetic efficiency as one-pot methodology, but they have also become an enabling tool for interdisciplinary research. The highly diversity-oriented nature of the synthetic concept allows accessing huge structural and functional space. Already some decades ago this has been recognized for life sciences, in particular, lead finding and exploration in pharma and agricultural chemistry. The quest for novel functional materials has also opened the field for diversity-oriented syntheses of functional π-systems, i.e. dyes for photonic and electronic applications based on their electronic properties. This review summarizes recent developments in MCR syntheses of functional chromophores highlighting syntheses following either the framework forming scaffold approach by establishing connectivity between chromophores or the chromogenic chromophore approach by de novo formation of chromophore of interest. Both approaches warrant rapid access to molecular functional π-systems, i.e. chromophores, fluorophores, and electrophores for various applications.

Mitochondria-Targeted Luminescent Organotin(IV) Complexes: Synthesis, Photophysical Characterization, and Live Cell Imaging

Five fluorescent ONO donor-based organotin(IV) complexes, [Sn^IV(L^1-5)Ph₂] (1-5), were synthesized by the one-pot reaction method and fully characterized spectroscopically including the single-crystal X-ray diffraction studies of 2-4. Detailed photophysical characterization of all compounds was performed. All the compounds exhibited high luminescent properties with a quantum yield of 17-53%. Additionally, the results of cellular permeability analysis suggest that they are lipophilic and easily absorbed by cells. Confocal microscopy was used to examine the live cell imaging capability of 1-5, and the results show that the compounds are mostly internalized in mitochondria and exhibit negligible cytotoxicity at imaging concentration. Also, 1-5 exhibited high photostability as compared to the commercial dye and can be used in long-term real-time tracking of cell organelles. Also, it is found that the probes (1-5) are highly tolerable during the changes in mitochondrial morphology. Thus, this kind of low-toxic organotin-based fluorescent probe can assist in imaging of mitochondria within living cells and tracking changes in their morphology.

Organotin Schiff bases as halofluorochromic dyes: green synthesis, chemio-photophysical characterization, DFT, and their fluorescent bioimaging in vitro

Fluorescent bioimaging is an excellent tool in cellular biology, and it will be a powerful technique in modern medicine as a noninvasive imaging technology where tumoral and normal cells must be distinguished. One of the differences between normal and cancer cells is the intracellular pH. Therefore, the design and synthesis of pH-responsive fluorescent materials are required. Organotin Schiff bases showed halofluorochromic behavior in solution. Microwave-assisted synthesis showed better reaction times and chemical yields compared with conventional heating. All compounds were fully characterized by spectroscopic and spectrometric techniques. The halofluorochromism study showed that some molecules in acidic media have the maximum luminescence intensity due to protonation. All the fluorescent tin complexes showed cell staining on hepatocyte and MCF-7 cells by confocal microscopy. The theoretical study has enabled us to rationalize the optical properties and the halofluorochromism for compounds 1 and 2 synthesized in this work. Our results showed that the emission decrease, in the acid and basic media for compounds 1 and 2, respectively, is caused by intramolecular charge transfer (ICT) deactivation.

Effect of Silk Fibroin on Cell Viability in Electrospun Scaffolds of Polyethylene Oxide

In this study, a coating from electrospun silk fibroin was performed with the aim to modify the surface of breast implants. We evaluated the effect of fibroin on polymeric matrices of poly (ethylene oxide) (PEO) to enhance cell viability, adhesion, and proliferation of HaCaT human keratinocytes to enhance the healing process on breast prosthesis implantation. We electrospun six blends of fibroin and PEO at different concentrations. These scaffolds were characterized by scanning electron microscopy, contact angle measurements, ATR-FTIR spectroscopy, and X-ray diffraction. We obtained diverse network conformations at different combinations to examine the regulation of cell adhesion and proliferation by modifying the microstructure of the matrix to be applied as a potential scaffold for coating breast implants. The key contribution of this work is the solution it provides to enhance the healing process on prosthesis implantation considering that the use of these PEO⁻fibroin scaffolds reduced (p < 0.05) the amount of pyknotic nuclei. Therefore, viability of HaCaT human keratinocytes on PEO⁻fibroin matrices was significantly improved (p < 0.001). These findings provide a rational strategy to coat breast implants improving biocompatibility.

Fluorescent organotin compounds as dyes in silk fibroin (Bombyx mori): ultrasound-assisted synthesis, chemo-optical characterization, cytotoxicity, and confocal fluorescence microscopy

The fluorescent silk fibroin (FSF) is useful in a number of biomedical applications.

Organotin Dyes Bearing Anionic Boron Clusters as Cell-Staining Fluorescent Probes

Within the cell nucleus, in the nucleoli, ribosomal RNAs are synthesized and participate in several biological processes. To better understand nucleoli-related processes, their visualization is often required, for which specific markers are needed. Herein, we report the design of novel fluorescent organotin compounds derived from 4-hydroxy-N'-((2-hydroxynaphthalen-1-yl)methylene)benzohydrazide and their cytoplasm and nucleoli staining of B16F10 cells in vitro. Tin compounds bearing an aliphatic carbon chain (-C₁₂ H₂₅ ) and an electron-donating group (-OH) were prepared, and the latter could be derivatized to bear the boron cluster anions [B₁₂ H₁₂ ]^2- and [3,3'-Co(1,2-C₂ B₉ H₁₁ )₂ ]^- (COSAN). All of the conjugates have been fully characterized and their luminescence properties have been assessed. In general, they show good quantum yields in solution (24-49 %), those for the COSAN derivatives being lower. Remarkably, the linking of [B₁₂ H₁₂ ]^2- and COSAN to the complexes made them more soluble, without being detrimental to their luminescence properties. Living B16F10 cells were treated with all of the compounds to determine their fluorescence staining properties; the compounds bearing the aliphatic chain showed a reduced staining capacity due to the formation of aggregates. Notably, the complexes bearing different boron clusters showed different staining effects; those bearing [B₁₂ H₁₂ ]^2- showed extraordinary staining of the nucleoli and cytoplasm, whereas those bearing COSAN were only detected in the cytoplasm. The remarkable fluorescence staining properties shown by these organotin compounds make them excellent candidates for fluorescence bioimaging in vitro.

One-pot microwave-assisted synthesis of organotin Schiff bases: an optical and electrochemical study towards their effects in organic solar cells

One-pot microwave synthesized organotin compound has been employed as good electro-acceptor (EA) and cheap for organic photovoltaic (OPV) solar cells.

Fluorescent biogenic Schiff base compounds of dimethyltin

Fluorescent biogenic Schiff base compounds of dimethyltin featuring distinct coordination sphere in solid and solution phase.

Exploration of fluorescent organotin compounds of α-amino acid Schiff bases for the detection of organophosphorous chemical warfare agents: quantification of diethylchlorophosphate

Fluorescent Schiff base organotin probes for the detection of chemical warfare agents.