Download or read book Synthesis and Characterization of a New Class of Mixed Ligand Ruthenium Complexes Containing 2 2 bipyridine and 3 3 dimetheyl 1 1 methylenebisimidazolium Carbene Ligands written by Ryan Mahabir and published by . This book was released on 2011 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Characterization of Hybrid Drugs Based on Ruthenium Complex Moiety and Biologically Active Organic Compounds written by Michał Pawel Łomzik and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main goal of this thesis was synthesis and preliminary characterization of novel ruthenium(II) polypyridyl complexes bearing biologically active molecules as potential theranostic agents. Luminescence for the diagnostic applications, and cytotoxicity for the anticancer, therapeutic applications are considered as the theranostic properties. Four new ligands containing biologically active moieties - 5-(4-4'-methyl-[2,2'-bipyridine]-4-ylbut-1-yn-1-yl)pyridine-2-carbaldehyde semicarbazone (L1), 3-(5-4'-methyl-[2,2'-bipyridine]-4-ylpentyl)imidazolidine-2,4-dione (L2), 5,5-dimethyl-3-(5-4'-methyl-[2,2'-bipyridine]-4-ylpentyl)imidazolidine-2,4-dione (L3) and [1-(5-4'-methyl-[2,2'-bipyridine]-4-ylpentyl)-2,5-dioxoimidazolidin-4-yl]urea (L4) were synthesized and characterized. The ligands were used to obtain nine novel ruthenium(II) polypyridyl complexes. Six complexes were synthesized with ligand L1 ([Ru(bpy)2(L1)]2+, [Ru(Mebpy)2(L1)]2+, [Ru(tBubpy)2(L1)]2+, [Ru(Phbpy)2(L1)]2+, [Ru(dip)2(L1)]2+, [Ru(SO3dip)2(L1)]2-) and three with ligands L2, L3 and L4 ([Ru(bpy)2(L2)]2+, [Ru(bpy)2(L3)]2+, [Ru(bpy)2(L4)]2+) (bpy = 2,2'-bipyridine, Mebpy = 4,4'-dimethyl-2,2-bipyridine, tBubpy = 4,4'-tert-butyl-2,2'-bipyridine, Phbpy = 4,4'-diphenyl-2,2-bipyridine, dip = 4,7-diphenyl-1,10-phenantroline and SO3dip = 4,7-di-(4-sulfonatophenyl)-1,10-phenantroline). The spectroscopic and photophysical properties of those complexes were determined. The presence of ligands L1-L4 in the structure of the complex decreased luminescence quantum yield and luminescence lifetime in comparison with unmodified [Ru(bpy)3]2+ complex. The theoretical calculations have shown that ligands L1-L4 do not have influence on ruthenium core geometry. However, they increased the energy of the HOMO that resulted in a shorter band gap. The simulated electronic absorption spectra were in a good agreement with the experimental data. The interactions between the studied ruthenium complexes and human serum albumin (HSA) were investigated. All studied Ru(II) complexes exhibited strong affinity to HSA with the association constant 105 M-1s-1, which suggests formation of Ru complex-HSA adducts. It was also determined that ruthenium complexes most likely bind to the hydrophobic pocket of protein, located in Sudlow's site I in the subdomain II A. Preliminary cytotoxicity evaluation for the studied ruthenium complexes showed their cytotoxic activity towards cancer cell lines. Those results, together with good luminescence properties of the studied ruthenium complexes (luminescence lifetimes and luminescence quantum yield) make them interesting candidates for potential theranostic applications.
Download or read book Synthesis Reactivity and Characterization of Ruthenium Complexes Containing a Single Bipyridine Ligand written by Simon I. Barsoum and published by . This book was released on 1989 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Design Synthesis and Characterization of Ruthenium ii and Rhenium i Complexes with Functionalized Ligands for Photo And Electrochemi Luminescence Solvatochromism Molecular Recognition and HPLC Separation Studies written by Meijin Li and published by Open Dissertation Press. This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Design, Synthesis and Characterization of Ruthenium(II) and Rhenium(I) Complexes With Functionalized Ligands for Photo-and Electrochemi- Luminescence, Solvatochromism, Molecular Recognition and HPLC Separation Studies" by Meijin, Li, 李梅金, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled DESIGN, SYNTHESIS AND CHARACTERIZATION OF RUTHENIUM(II) AND RHENIUM(I) COMPLEXES WITH FUNCTIONALIZED LIGANDS FOR PHOTO- AND ELECTROCHEMI- LUMINESCENCE, SOLVATOCHROMISM, MOLECULAR RECOGNITION AND HPLC SEPARATION STUDIES Submitted by LI MEIJIN for the degree of Doctor of Philosophy at The University of Hong Kong in July 2006 A series of ruthenium(II) and rhenium(I) diimine complexes containing thia-, selena- and aza-crowns derived from 1,10-phenanthroline, [Ru(bpy) (phen-3S)](ClO ) 2 4 2 (phen-3S = 1,13-dioxa-4,7,10-trithiacyclopentadecano[2,3-f][1,10]phenanthroline), [Ru(bpy) (phen-2S)](ClO ) (phen-2S = 1,7,10,16-tetraoxa-4,13-dithiacyclohexa- 2 4 2 dodecano[2,3-f][1,10]phenanthroline), [Ru(bpy) (phen-S)](ClO ) (phen-S = 1,4,10,13- 2 4 2 tetraoxa-7-thiacyclopentadecano[2,3-f][1,10]phenanthroline), [Ru(bpy) (phen-Se)](ClO ) 2 4 2 (phen-Se = 1,4,10,13-tetraoxa-7-selenacyclopentadecano[2,3-f][1,10]phenanthroline), [Ru(bpy) (phen-OEt](ClO ) (phen-OEt = 5,6-diethoxy-[1,10]phenanthroline), 2 4 2 [Ru(bpy) (phen-2NH)](ClO ) (phen-2NH = 1,13-diaxa-4,7,10-trioxacyclopenta- 2 4 2 decano[2,3-f][1,10]phenanthroline), [Re(CO) (py)(phen-3S)]PF, [Re(CO) (py)(phen-S)]OTf 3 6 3 and [Re(CO) (py)(phen-Se)]OTf have been synthesized and characterized, and their photophysics, electrogenerated chemiluminescence (ECL) and electrochemistry were studied. Their interaction with metal ions was investigated by UV-vis, luminescence, NMR spectroscopy and ECL. [Ru(bpy) (phen-3S)](ClO ) and [Re(CO) (py)(phen-3S)]
Download or read book Diimine Complexes of Ruthenium ii Rhenium i and Iron ii from Synthesis to DFT Studies written by R. A. Kirgan and published by . This book was released on 2007 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt: [Author's abstract] The chloro and pyridinate derivatives of rhenium(I) tricarbonyl complexes containing the diimine ligands 2,2'-bipyrazine (bpz) and 5,5'-dimethyl-2,2'-bipyrazine (Me2bpz) are discussed. When compared to similar rhenium(I) tricarbonyl complexes of 2,2'-bipyridine (bpy) and 2,2'-bipyrimidine (bpm), the Me2bpz complexes are comparable to bpm derivatives and their properties are intermediate between those of bpy and bpz complexes. Also discussed is the synthesis and properties of two new analogues of ruthenium(II) tris-bipyridine, a monomer and dimer. The complexes contain the ligand 6,6'-(1,2-ethanediyl)bis-2,2'-bipyridine (O-bpy) which contains two bipyridine units bridged in the 6,6' positions by an ethylene group. Crystal structures of the two complexes formulated as [Ru(bpy)(O-bpy)](PF6)2 and [(Ru(bpy)2)2(O-bpy)](PF6)4 reveal structures of lower symmetry than D3 which affects the electronic properties of the complexes as revealed by Density Functional Theory (DFT) and Time Dependent Density Functional Theory (TDDFT) calculations. Iron(II) tris-bipyrazine undergoes dissociation in solution with loss of the three bipyrazine ligands. The rate of the reaction in acetonitrile depends on the concentration of anions present in the solution. The rate is fastest in the presence of Cl- and slowest in the presence of Br-. In a second discussion DFT calculations are used to explore four iron(II) diimine complexes. DFT calculations show the higher energy HOMO (highest occupied molecular orbital) orbitals of the four complexes are metal centered and the lower energy LUMO (lowest unoccupied molecular orbitals) are ligand centered.
Download or read book Synthesis and Characterization of Ruthenium Complexes with N N P P and N P 2 Donor Sets written by Xinwei Yang and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the discovery of nonlinear effects, both the theory and measurement techniques have been developed significantly, especially since the invention of the laser. However, structure-NLO property relationships for organometallics as well as their NLO mechanisms are far less explored than those of organic molecules and inorganic salts. The greater flexibility and exceptionally large NLO responses of organometallic compounds attracts chemists to this field. Modification of coordinated co-ligands in organometallic systems has influence on the NLO merit by introducing new electronic charge-transfer transitions, oxidation state and coordination sphere of the metal centers. In this work, the donor sets of the ruthenium complexes were modified from the most investigated (P-P)(P-P) to (N-N)(P-P) and (N-P)2 and a series of ruthenium complexes were synthesized and characterized. In Chapter 2, the study of the Ru(N-N)(P-P) complexes is detailed. Three bidentate diphosphine ligands (dppe, dppb and dppf) and one diimine ligand (tert-Bu-bpy) were selected for this study as the diphosphine and diimine ligands, respectively. Ruthenium halide and mono-alkynyl complexes were obtained successfully. Their optical, electrochemical and spectroelectrochemical properties were examined and are discussed. The formation of eta3- and eta1-butenynyl complexes was confirmed by single-crystal X-ray diffraction. Attempts towards bis-alkynyl complexes were made, but no conclusive evidence could be obtained to confirm the successful synthesis of this species. In Chapter 3, the focus of the work is the study of ruthenium complexes with a (N-P)2 donor set. Two iminophosphine ligands, 2-(diphenylphosphino)pyridine (PPh2py) and 8-(diphenylphosphino)quinoline (PPh2qn), were selected for this study. The cis-RuCl2(N-P) complexes and the corresponding dimers were synthesized and characterized. Their optical and electrochemical properties were measured and are discussed. In Chapter 4, the quadratic and cubic nonlinear optical properties of organometallic complexes were explored by hyper-Rayleigh scattering (HRS) and frequency-depentdent Z-scan techniques, respectively. The first hyperpolarizabilities of the ruthenium halide and mono-alkynyl complexes described in Chapter 2 were determined by HRS measurements. The second hyperpolarizabilities of some organometallic complexes synthesized by the Humphrey group and the collaborators were measured by the Z-scan technique.
Download or read book Synthesis and Photophysical Studies of Ruthenium II Complexes Containing the Ligand 1 2 BIS 2 2 bipyridyl 6 yl Ethane written by Ariel V. Macatangay and published by . This book was released on 1994 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Characterization of Some New Polypyridine Ruthenium II Complexes Containing S bonded Thioether Ligands written by Rudi Kroener and published by . This book was released on 1984 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ruthenium II Complexes of Mixed Bipyridyl and Dithiolate thiourea Ligands written by Pelokazi Nkombi and published by . This book was released on 2018 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Synthesis Characterization and Reactivity of Ruthenium Complexes Containing Tris pyrid 2 yl methoxymethane written by Laura M. Witham and published by . This book was released on 1997 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Characterization of New Rhodium carbene and New Iron carbene Complexes written by Matthew Ryan and published by . This book was released on 2013 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Beyond Click Chemistry written by Benjamin Schulze and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Synthesis Characterization and Photophysical Properties of Ruthenium II Bis 4 4 dimethyl 2 2 bypyridine i e Bipyridine bis pyridine and Its Analogues written by David Wilson Wright and published by . This book was released on 1988 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Characterization of Ruthenium II and Platinum IV Complexes with Anionic Heteroatomic Ligands written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Isolated and fully characterized complexes of late transition metals in low oxidation states possessing amido and alkoxo ligands are relatively rare. These ligands often exhibit nucleophilic and/or basic reactivity. This reactivity is due, at least in part, to the disruption of ligand to metal à â'Ơ-bonding. Reports of early transition metals with low d-electron counts with imido ligands facilitating C-H activation suggest that if later transition metals with amido or aryloxo ligands can be isolated, C-H activation reactivity may be observed. Ruthenium(II) complexes that catalyze the H/D exchange of N-H and O-H protons at anilido and hydroxo ligands, respectively, with deuterated solvents have been reported, and studies of related systems could shed significant light on C-H activation in these types of reactions. Observing changes in the rate of C-H activation based on specific changes to transition metal complexes could give insight into the creation of highly active C-H activation catalysts. Presented here are synthetic efforts toward late transition metal complexes with formally anionic heteroatomic ligands. The synthesis and initial characterization of [EpRu(Cl)(PPh3)(NCMe)][Cl], [EpRu(py)2Cl][Cl], [EpRu(py)2Cl][Cl], [EpRu(OHMe)(PMe3)(Cl)][BArÃØâ'Ơâ"Ø4] are reported {Ep = 1,1,1-tris(pyrazolyl)ethane, py = N-pyridine, ArÃØâ'Ơâ"Ø = 3,5-(CF3)-C6H3}. The lack of solubility yielded these complexes ineffective for further synthetic manipulation. Additionally presented is the synthesis and characterization of (tbpy)Pt(Me)2(I)2 and (tbpy)Pt(Me)(NHPh)(I)2 (tbpy = 4,4ÃØâ'Ơâ"Ø-tert-butyl-2,2ÃØâ'Ơâ"Ø-bipyridine). Attempted syntheses of (tbpy)Pt(NHPh)2(I)2 and (tbpy)Pt(Cl)(NHPh)(I)2 are also reported. Initial reactivity of (tbpy)Pt(Me)2(I)2 and the decomposition of (tbpy)Pt(Me)(NHPh)(I)2 are further re.
Download or read book Ruthenium N Heterocyclic Carbene and Ruthenium Acetylide Complexes Supported by Macrocyclic Porphyrin Or Tetradentate Schiff Base Ligands written by Ka-Ho Chan and published by Open Dissertation Press. This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Ruthenium-N-heterocyclic Carbene and Ruthenium Acetylide Complexes Supported by Macrocyclic Porphyrin or Tetradentate Schiff Base Ligands: Synthesis, Structure and Catalytic Applications" by Ka-ho, Chan, 陳嘉豪, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled RUTHENIUM-N-HETEROCYCLIC CARBENE AND RUTHENIUM ACETYLIDE COMPLEXES SUPPORTED BY MACROCYCLIC PORPHYRIN OR TETRADENTATE SCHIFF BASE LIGANDS: SYNTHESIS, STRUCTURE AND CATALYTIC APPLICATIONS Submitted by Chan Ka Ho for the degree of Doctor of Philosophy at The University of Hong Kong in March 2015 Transition metal-catalyzed C-C and C-N bond formation reactions are important transformations in synthetic organic chemistry. In the endeavor of this thesis to develop robust/versatile catalysts for these reactions, the trans effect imposed by N-heterocyclic carbene (NHC) and acetylide ligand onto ruthenium complexes supported by macrocyclic porphyrin or tetradentate Schiff-base ligands was studied. The catalytic activity of these novel ruthenium complexes towards carbene and/or nitrene transfer and insertion reactions was also explored. II A series of bis(NHC)ruthenium(II) porphyrin complexes [Ru (Por)(NHC) ] were synthesized by deprotonation of imidazolium salt using a strong base. These complexes displayed unprecedentedly high catalytic activity towards carbene/nitrene transfer and insertion reactions, including alkene cyclopropanation and aziridination, carbene C-H, S-H, N-H and O-H insertions, and nitrene C-H insertion with product -1 turnover frequency up to 1950 min . Carbene modification of N-terminus of peptide o II at 37 C was achieved. Chiral [Ru (D -Por)(NHC) ] catalyst led to highly 4 2 enantioselective carbene/nitrene transfer and insertion reactions with up to 98% ee. DFT calculations revealed that the strong σ-donor strength of trans axial NHC ligand stabilizes the formation of metal-carbene and metal-nitrene intermediate from decomposition of diazo compounds and organic azides, which is crucial for the transition metal-catalyzed oxidative C-C and C-N bond formation reactions to proceed under mild reaction conditions. II A series of ruthenium Schiff-base complexes cis-β-[Ru (Schiff-base)(CO) ] were synthesized and characterized. These complexes showed high catalytic activity towards enantioselective cyclopropanation, carbene C-H and Si-H bond insertions. II t The cis-[Ru (2-CPh -4- Bu-Schiff-base)(CO) ]-catalyzed intermolecular 3 2 cyclopropanation of styrene with EDA in CH Cl afforded desired cyclopropane 2 2 product in 90% isolated yield and 95% ee with a product turnover number of 9000. Excellent trans- and high enantioselectivity were observed with wide substrate scope, including conjugated, electron-rich, electron-deficient and aliphatic terminal alkenes. Carbene C-H and Si-H insertion reactions proceeded smoothly with II t cis-[Ru (2-CPh -4- Bu-Schiff-base)(CO) ] as catalyst, giving the desired products in 3 2 82-97% yields with excellent enantioselectivity (up to 99% ee). The same complex was also catalytically active towards intramolecular cyclopropanation and intramolecular alkyl carbene sp C-H bond insertion to give cis-products with up to 99:1 cis: trans ratio and with excellent enantioselectivities (up to 98% ee). DFT calculations on the intermolecular cyclopropanation catalyzed by II cis-β-[Ru (Schiff-base)(CO) ] revealed that among the ruthenium-carbene intermediates possibly involved in the reactions, the cis-β species are more stable than their trans isomer with
Download or read book Design Synthesis and Reactivity of Bimetallic Complexes of Dimethylplatinum II Containing Ditopic Ligands written by Matthew S. McCready and published by . This book was released on 2015 with total page 658 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes a study of monometallic and bimetallic dimethylplatinum(II) complexes containing ditopic nitrogen donor ligands. This work details the design and synthesis of side-to-side and cofacial arranged ligands and their respective coordination chemistry. The study of the synthesis, characterization and reaction mechanisms of the various dimethylplatinum(II) complexes is outlined in detail with special emphasis focused on the reactivity of the complexes towards oxidative addition. The ditopic ligand 6-dppd, 1,4-di(2-pyridyl)-5,6,7,8,9,10- hexahydrocycloocta[d]pyridazine, was observed to coordinate only a single equivalent of a platinum(II) center. The inability to coordinate a second equivalent, even through an assisted bridging atom, is presumed to be due to a steric clash between the free pyridyl group and the cyclooctyl backbone. In attempts to make heterobimetallic complexes of 6-dppd, the complex [PtMe2(6-dppd)] was observed to react preferentially with mercuric halides by oxidative addition rather than coordination of the mercuric salt in the second coordination site giving complexes [PtXMe2(HgX)(6-dppd)] where X = Br, Cl, OAc. This indicates that the platinum center is actually a better nucleophile than the free pyridyl nitrogen atom. The oxidative addition of solvent dichloromethane was also observed showing the enhancedreactivity of [PtMe2(6-dppd)]. Finally, [PtMe2(6-dppd)] was treated with DCl at low temperature to give the deuteridoplatinum(IV) complex. The deuteridoplatinum(IV) complex reductively eliminates methane in solution and extensive H/D exchange occurs into the CH4 product at low temperature indicating very easy reversibility of the exchange between hydridomethylplatinum(IV) and methaneplatinum(II) complexes. The abstraction of a chloride ligand from [PtClMe(6-dppd)] led to the formation of a complex dimer structure endo, endo-[Pt2Me2(?2-?3-6-dppd)2][OTf]2. This process allowed for the formation of a bimetallic platinum(II) complex which retained the initial stereochemistry. The protonolysis of [PtMe2(6-dppd)] with one equivalent of HOTf led to the generation of methane gas and the concomitant formation of both endo, endo-[Pt2Me2(?2-?3-6-dppd)2][OTf]2 and exo, exo-[Pt2Me2(?2-?3-6-dppd)2][OTf]2. The structures of the exo isomeric clamshell dimers appeared much less sterically hindered in the solid state and were observed experimentally and computationally to be the thermodynamically preferred isomers. The mechanism, selectivity and reversibility of this isomerism process was explored in detail. The reactions of [PtMe2(6-dppd)] with alkyl bromides RCH2Br, which possess hydrogen bonding functionality, result in the formation of stable organoplatinum(IV) complexes capable of forming supramolecular structure via hydrogen bonding. Both intra and inter molecular hydrogen bonding is observed in the formation of supramolecular architectures which self-assemble in the solid state through additional?-stacking and weak secondary interactions. The new anthracene derived ditopic ligands, bpad = N1,N8-bis(pyridin-2- ylmethylene)anthracene-1,8-diamine and adpa = (N, N)-4,4'-(anthracene-1,8-diylbis(ethyne- 2,1-diyl))-bis(N-(pyridin-2-ylmethylene)aniline) were prepared, characterized and used to coordinate dimethylplatinum(II) centers giving cofacial bimetallic complexes of dimethylplatinum(II). [Pt2Me4(bpad)] was shown to degrade over time in solution through a proposed metalation event involving the anthracene backbone. The oxidative addition of a variety of substrates was performed using [Pt2Me4(adpa)] giving stable diplatinum(IV) complexes as characterized by 1H NMR spectroscopy. The new xanthene derived ditopic ligands, ppxda = 2,7-di-tert-butyl-9,9-dimethyl-N4,N5-bis(4-(pyridin-2- ylmethyleneamino)phenyl)-xanthene-4,5-dicarboxamide and pmxda = 2,7-di-tert-butyl-9,9- dimethyl-bis(pyridine-2-ylmethylene)-9H-xanthene-4,5-diamine were prepared characterized and used to ligate two equivalents of a dimethylplatinum(II) center. Diplatinum complexes of both ligands were shown to easily undergo oxidative addition to give the corresponding diplatinum(IV) complexes which adopt the anti orientation. The syn alignment of metal centers was accessible through the abstraction of halides ligands and incorporation of bridging groups as is the case for the pyrazine bridged bimetallic platinum complex [Pt2Me6(C4H4N2)(pmxda)][OSO2CF3]2.
Download or read book Synthesis and Characterization of Photolabile Ruthenium Polypyridyl Crosslinkers with Applications in Soft Materials and Biology written by Teresa Rapp and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since its discovery in 1844, ruthenium has solidified its position as the most widely used transition metal in catalysis and excited state chemistry. Its lower toxicity and relatively low price (compared to other platinum group metals) have enabled many applications of ruthenium coordination compounds. In this dissertation I discuss ruthenium polypyridyl complexes that undergo photoinduced ligand exchange, and how this unique property can be harnessed to develop next-generation smart materials and responsive chemical biology tools. Ru(LL)2X22+ complexes, where LL is a bidentate aromatic heterocycle such as 2,2'-bipyridine, 1,10-phenanthroline, or 2,2'-biquinoline, and X is a pyridine-, nitrile-, sulfur-, or imidazole-based monodentate ligand, have the unique capability to undergo ligand exchange under visible light irradiation. We have harnessed this property to develop a series of visible-light-sensitive photodegradable crosslinkers by choosing X ligands that contain reactive moieties such as alkynes (for copper-mediated azide-alkyne cycloaddition (CuAAC)) or aldehydes (for Schiff base reaction with hydrazines). Ru(bpy)2(3-ethynylpyridine)2 (RuBEP) has been used in CuAAC reactions to circularize azide-terminated oligonucleotides important for gene regulation or transcriptome analysis. Ru(bpy)2 (3-pyridinaldehyde) 2 (RuAldehyde) alternately employed aldehydes to react with hydrazine-modified hyaluronic acid (HA-HYD). The resulting hydrogel was cytocompatible, efficiently degraded with visible light, and well adapted for the storage and delivery of active enzymes via lysine-mediated crosslinking into the hydrogel matrix. Finally, Ru(biq)2(5-hexynenitrile)2 and Ru(bpy) 2(5-hexynenitrile) 2 were developed as crosslinkers to form PEG-based hydrogel, which was subsequently degraded using two different colors of visible light, orange and blue.
