Excited state proton transfer studies of six Ru polypyridyl compounds with carboxylic acid/carboxylate group(s) revealed that some were photoacids and photobases. The [Ru(II)(btfmb)2(LL)](2+), [Ru(II)(dtb)2(LL)](2+), [Ru(II)(bpy)2(LL)](2+), where bpy is 2,2'-bipyridine, btfmb 4,4'-(CF3)2-bpy, dtb 4,4'-((CH3)3C)2-bpy, LL either dcb = 4,4'-(CO2H)2-bpy or mcb 4-(CO2H),4'-(CO2Et)-2,2'-bpy, synthesized characterized. exhibited intense metal-to-ligand charge-transfer (MLCT) absorption bands in the...

Abstract— The action spectrum for photoreactivation has been determined in a coccoid blue‐green alga, Agmenellum quadruplicatum. is rather similar to that recorded Streptomyces griseus conidia, with some suggestion of little more structure. suggests possible carotenoid involvement; however, no other evidence this could be found. u.v. killing also broad fine implication tetrahydropteridines or c ‐phycocyanin as chromophores the region 240–300 nm, along DNA, pointed out.

The photophysical and electron transfer properties of mesoporous nanocrystalline (anatase) TiO2 thin films sensitized to visible light with [Ru(dtb)2(dcb)](PF6)2, where dtb is 4,4′-(tert-butyl)2-2,2′-bipyridine dcb 4,4′-(CO2H)2-2,2′-bipyridine, were quantified in acetonitrile solutions that contained 100 mM concentrations Li+, Na+, Mg2+, or Ca2+ perchlorate salts. presence these salts resulted a dramatic cation dependent bathochromic (red) shift the metal-to-ligand charge (MLCT) absorption...

Remarkably little is known about metal-to-ligand charge transfer (MLCT) excited-state relaxation pathways for the ruthenium polypyridyl compounds commonly utilized in dye-sensitized solar cells. Herein, we report variable-temperature photoluminescence studies of general type cis-Ru(LL)2(X)2, where LL a bipyridyl ligand and X CN(-) or NCS(-), contrast them with well-known Ru(bpy)3(2+) Os(bpy)3(2+), bpy 2,2'-bipyridine, to identify pathways. In fluid acetonitrile propylene carbonate solutions,...

Excited-state electron injection at a sensitized TiO2 electrolyte interface generates significant electric field. Ions and solvent molecules in the respond to this field reorganize from their dark equilibrium condition. Here we report first kinetic study of such interfacial reorganization with acetonitrile electrolytes that contain LiClO4 or Mg(ClO4)2. The Mg2+ ions were found most effectively shield surface-anchored sensitizers fields, but rates screening much slower than Li+. Kinetic...

The electric fields generated by excited-state electron injection into anatase TiO2 nanocrystallites are screened cations present in the external electrolyte. With some assumptions, a newly discovered electroabsorption signature enables quantification of field strength experienced surface-anchored dye molecules. Here, it was found that increased order Na+ < Li+ Mg2+ Ca2+, with magnitudes 1.1 MV/cm for and 2.2 values were insensitive to whether anion iodide or perchlorate. magnitude directly...

Self-exchange intermolecular RuIII/II electron transfer, a process commonly referred to as "hole-hopping", is of great interest it provides means charge transport across the surface nanocrystalline (anatase) TiO2 mesoporous thin films without loss free energy. This was characterized by cyclic voltammetry and chronoabsorptometry for three homologous Ru diimine compounds general form [Ru(LL)2(dcbH2)](PF6)2, where LL 2,2′-bipyridine (bpy), 4,4′-dimethyl-2,2′-bipyridine (dmb), or...

Mesoporous TiO2 thin films sensitized to visible light with [Ru(dtb)2(dcb)]2+, where dtb is 4,4′-((CH3)3C)2-2,2′-bipyridine and dcb 4,4′-(CO2H)2-2,2′-bipyridine, abbreviated TiO2|Ru, were investigated in acetonitrile electrolytes that contained 0.1 M Na+, Li+, Mg2+, or Ca2+ perchlorate solutions the electron donor trip-tolylamine (TPTA) phenothiazine (PTZ). Pulsed 532 nm excitation of TiO2|Ru >25 mM concentrations quantitatively yielded TiO2(e–)|Ru + D+, corresponding recombination reaction...

Comprehensive investigations of the linear and nonlinear optical properties new Ir(III) complexes [Ir(pbt)2(dbm)] (1), [Ir(pbt)2(dmac)] (2), [Ir(pbt)2(minc)] (3) (pbt = 2-phenylbenzothiazole; dbm dibenzoyl methane; dmac (1E,4Z,6E)-1,7-bis(4-(dimethylamino)phenyl)-5-hydroxyhepta-1,4,6-trien-3-one; minc (1E,4Z,6E)-5-hydroxy-1,7-bis(1-methyl-1H-indol-3-yl)hepta-1,4,6-trien-3-one) are reported, including photostability, two-photon absorption, femtosecond transient absorption spectroscopy. The...

The sensitizer [Ru(dtb)2(dcb)]2+, where dtb is 4,4′-di-tert-butyl-2,2′-bipyridine and dcb 4,4′-dicarboxylic acid-2,2′-bipyridine, was anchored to mesoporous TiO2 thin films characterized by visible spectroscopy in 0.1 M Na+, Li+, Mg2+, Ca2+ perchlorate acetonitrile solutions on nanosecond longer time scales. Relative neat acetonitrile, the presence of these electrolyte cations induced a red shift metal-to-ligand charge transfer (MLCT) absorption Ru(dtb)2(dcb)/TiO2. magnitude increased with...

Nonlinear optical properties were characterized for a series of multinuclear iridium compounds the form TCQ[IrIII(ppz)2]n, where n=1, 2, or 3, TCQ is tricycloquinazoline, and ppz 1-phenylpyrazole. Transient absorption (TA) spectroscopy indicated that triplet metal-to-ligand charge transfer excited state was formed on subpicosecond time scale decayed back to ground microsecond scale, consistent with precedents in literature. TA bands observed all three from 475 900 nm, implying potential...

Nonlinear optical (NLO) materials are able to modulate responses of electromagnetic radiation, leading phenomena critical modern telecommunications technologies. The last two decades have seen significant advances in the area molecular nonlinear chromophores, particularly with respect reverse-saturable absorption (RSA). Here, we introduce a strategy for intense excited-state (ESA) that involves bis-cyclometalated iridium complexes isocyanide ancillary ligands decorated pyrene triplet...

Excited-state absorption, triplet lifetimes, and triplet–triplet annihilation rate constants can be tuned by structural modifications.

In this work, we introduce a series of cyclometalated iridium complexes and evaluate the suitability class compounds in nonlinear optical (NLO) applications, with an emphasis on long-lived, panchromatic reverse-saturable absorption (RSA). The investigated are represented by general formula [Ir(C^N)2(CNArdmp)2]+, (C^N = cyclometalating ligand, CNArdmp 2,6-dimethylphenyl isocyanide). Seven such were synthesized characterized, including in-depth analysis their photophysical properties (UV-vis...

Linear steady-state and time-resolved spectroscopic properties, degenerate two-photon absorption (2PA) spectra, photochemical stability of IrIII complexes TCQ[IrIII(ppz)2]n, (TCQ = tricycloquinazoline; ppz 1-phenylpyrazole; n 1 (1), 2 (2), 3 (3)) are presented for liquid solutions. The analysis the linear photophysical properties revealed nature observed dual-component fluorescence–phosphorescence emission 1–3 at room temperature. values 2PA cross sections were determined by open aperture...

We report a general, photochemical method for the rapid deoxygenation of organic solvents and aqueous solutions via visible light excitation transition metal chromophores (TMCs) in presence singlet oxygen scavenging substrates. Either 2,5-dimethylfuran or an amino acid (histidine tryptophan methyl ester) was used as substrate conjunction with iridium ruthenium TMC toluene, acetonitrile, water. This behavior is described chromophore concentrations that are pertinent both luminescence...

Two ruthenium compounds were anchored to mesoporous nanocrystalline TiO2 thin films probe local electric fields generated by reduction or cation adsorption in acetonitrile electrolytes. The metal-to-ligand charge-transfer (MLCT) excited states well formulated as [RuIII(dtb)2(dcb–)]2+* and [RuIII(btfmb)(dcb)(btfmb–)]2+*, where dtb is 4,4′-(tert-butyl)2-2,2-bipyridine, dcb 4,4′-(CO2H)2-2,2-bipyridine, btfmb 4,4′-(CF3)2-2,2-bipyridine. MLCT state was orientated toward the surface linker...

Despite 40 years of interest in chalcogenopyrylium polymethine dyes, significant gaps remain our understanding their photophysical properties. These hinder efforts to apply such dyes as photodynamic therapy and/or biomedical sensing agents where a complete excited-state dynamics and chemistry are important. For example, despite previous reports that establish singlet oxygen yields high 12% for certain we observe no evidence 1O2 from direct phosphorescence measurements. We now fill many these...

We performed a comprehensive study of the fast relaxation processes in three metal–organic Ir(III)-complexes liquid solutions at room temperature order to estimate their singlet–triplet conversion quantum yields, ΦST. Experimental pico- and femtosecond transient absorption double pump–probe spectroscopy techniques were employed reveal peculiarities triplet population processes, corresponding values ΦST obtained based on six-level electronic model. Our results confirm triplets that has been...

Transition metal complexes are utilized in a broad array of applications such as photoredox catalysis, photodynamic therapy, biological sensing, and phosphors for organic light-emitting diodes. Furthermore, many transition metals demonstrate two photon absorption reverse saturable (RSA) characteristics increasing their non-linear optical materials. Iridium is particular interest to our work because its strong spin-orbit coupling, which allows multiple excited states, thereby the compound's...

This research focuses on integrating supramolecular chemistry and reverse saturable absorption (RSA) principles, focusing combining pillar[5]arene frameworks with metal-complexed ligands. By delving into these systems' theoretical underpinnings potential applications, we shed light the synergistic effects that may arise from this innovative approach. We envision promising advancements in photonic electronic materials by unique structural properties of pillar[5]arenes RSA Although specific...

Here, we present our development of several experimental methods, which, when applied together, can provide a thorough characterization the nonlinear refraction and absorption properties materials. We focus mainly on time-resolved methods for studying both transient that reveal molecular dynamics including excited-state absorption, singlet-triplet transfer, instantaneous electronic refraction, reorientation. In particular, will describe recent studies new materials organometallic compounds...