Raquel E Galian

University of Valencia | UV · Instituto de Ciencia Molecular (ICMol)

We illustrate here the high photocatalytic activity of sustainable lead-free metal halide nanocrystals (NCs), namely, Cs3Sb2Br9 NCs, in the reduction of p-substituted benzyl bromides in the absence of a cocatalyst. The electronic properties of the benzyl bromide substituents and the substrate affinity to the NC surface determine the selectivity in...

Surface chemistry and quantum confinement in nanocrystals (NCs) can modulate the energy transfer efficiency between lead halide perovskite (LHP) NCs and acceptor molecules in hybrid assemblies. It is demonstrated here that colloidal CsPbBr3 NCs capped with the oleic acid/oleylamine ligand pair act as a good singlet sensitizer of meso-(4-carboxyphen...

A variety of phenols have been obtained in aqueous media with moderate to excellent chemical yields (≤100%) by using arylboronic acids and esters as substrates, a robust CdS-TiO2 nanohybrid as a heterogeneous photocatalyst, visible light irradiation (467 nm), and an O2-saturated atmosphere. The nanohybrid was prepared through a linker-assisted meth...

This annual review, the 50th volume in the series, provides critical analysis for anyone wanting to keep up to date with the literature on photochemistry and its applications. This essential volume combines reviews on the latest advances in photochemical research with specific topical highlights in the field. The volume starts with periodical repor...

All-inorganic lead halide perovskite nanocrystals have great potential in optoelectronics and photovoltaics. However, their biological applications have not been explored much owing to their poor stability and shallow penetration depth of ultraviolet (UV) excitation light into tissues. Interestingly, the combination of all-inorganic halide perovski...

The long-standing debate about the morphology of colloidal methylammonium lead bromide perovskites nanocrystals, manufactured by our nontemplate synthetic strategy reported in 2014, is now resolved; specifically, the highest green emissive...

Ruddlesden-Popper lead halide perovskite (RP-LHP) nano-nanostructures can be regarded as self-assembled quantum wells or superlattices of 3D perovskites with an intrinsic quantum well thickness of a single or a few (n=2-4) lead halide layers; the quantum wells are separated by organic layers. They can be scaled down to a single quantum well dimensi...

Ruddlesden‐Popper lead halide perovskite (RP‐LHP) nano‐nanostructures can be regarded as self‐assembled quantum wells or superlattices of 3D perovskites with an intrinsic quantum well thickness of a single or a few ( n =2‐4) lead halide layers; the quantum wells are separated by organic layers. They can be scaled down to a single quantum well dimen...

This review focuses on the recent developments in synthesis, properties, and applications of a relatively new family of photoactive porous composites, integrated by metal halide perovskite (MHP) nanocrystals and metal-organic frameworks (MOFs). The synergy between the two systems has led to materials (MHP@MOF composites) with new functionalities al...

Metal-halide perovskites have rapidly emerged as one of the most promising materials of the 21st century, with many exciting properties and great potential for a broad range of applications, from photovoltaics to optoelectronics and photocatalysis. The ease with which metal-halide perovskites can be synthesized in the form of brightly luminescent c...

Sensitized emission of lead halide perovskite nanoparticles (LHPNPs) can be achieved by near‐infrared (NIR) excitation of nearby lanthanide‐doped upconversion nanoparticles (UCNPs) by using a low‐cost diode laser. Here, the first preparation of linear assemblies of core and core–shell NPs, as well as linear coassemblies of LHPNPs and UCNPs, within...

This article delineates the state of the art for several materials used in the harvest, conversion, and storage of energy, and analyzes the challenges to be overcome in the decade ahead for them to reach the market and benefit society. The materials covered have had a special interest in recent years and include perovskites, materials for batteries...

An array of hybrid lead halide CH3NH3Pb(Br/I)3 colloidal perovskites have been successfully synthesized by 532‐nm laser irradiation of either pure lead halide CH3NH3PbX3 (X=Br‐, I‐) or mixed‐halide CH3NH3PbBr3‐xIx bulks, by using 2‐adamantylammonium iodide and/or 2‐adamantylammonium bromide as the source for varying the perovskite halide content as...

The preparation of densely-packed films from hybrid lead halide perovskite nanocrystals is not trivial, as during assembly into the solid state both the charge transport and photoluminescence can be substantially altered. The objective of the present studies was to retain pre-engineered confined morphologies of hybrid lead halide perovskite nanocry...

A novel preparation of lead halide, CH3NH3PbBr3, perovskite nanoparticle solid films from colloidal “naked” nanoparticles, that is, dispersible nanoparticles without any surfactant, is reported. The colloids are obtained by simply adding potassium ions, whose counterions are both more lipophilic and less coordinating than bromide ions, to the perov...

Organolead halide perovskites have emerged as exciting optoelectronic materials but a complete understanding of their photophysical properties is still lacking. Here, a morphological series of methylammonium lead bromide (MAPbBr3) perovskites are studied by transient optical spectroscopies over eight orders of magnitude in timescale to investigate...

A novel nanoplatform composed of three types of materials with different functionalities, specifically core-shell Fe3O4@Au nanoparticles encapsulated near the outer surface of mesoporous silica (mSiO2) nanoparticles, has been successfully synthesised and used to enhance the efficiency of a photosensitiser, namely Rose Bengal, in singlet oxygen gene...

The mechanism responsible for the extremely long photoluminescence (PL) lifetimes observed in many lead halide perovskites is still under debate. While the presence of trap states is widely accepted, the process of electron de-trapping back to the emissive state has been mostly ignored, especially from deep traps as these are typically associated w...

CH3NH3PbBr3 perovskite nanoparticles (PAD) are prepared with a photoluminescence quantum yield of ≈100% in air atmosphere by using the quasi-spherical shaped 2-adamantylammonium bromide (ADBr) as the only capping ligand. The photostability under wet conditions of this kind of nanoparticles is enhanced by using cucurbit[7]uril-adamantylammonium (AD@...

Upconversion-perovskite nanohybrids are prepared by assembling CH3NH3PbBr3 perovskite nanoparticles (PK) with naked NaYF4:Yb3+,Tm3+ nanoparticles (UCn) via an innovative strategy consisting of using cucurbit[7]uril (CB[7]) to anchor the perovskite nanoparticles firmly and closely to the upconversion nanoparticles, thus leading to UCn@PKCB nanohybri...

We report the synthesis of a smart novel hybrid with reversible photoswitchable luminescence properties modulated by light. Combination of a low molecular weight organgelator (LMOG) and CdSe/ZnS core-shell semiconductor nanoparticles capped with trioctylphosphine oxide ligands produces a luminescent, stable and transparent material. Modulation of t...

Organic-inorganic (hybrid) and all-inorganic lead halide perovskites, in particular APbX3 where A is an organic cation (methylammonium or formamidinium) or cesium cation and X = Cl, Br, I, respectively, are of great interest in photovoltaic devices and as luminescent materials for light-emitting devices. It has recently been demonstrated that they...

A properly designed pyrene-capped CdSe/ZnS nanohybrid can act as a three-channel fluorescent sensor due to the independent emission of the pyrene monomer and excimer as well as that of the nanoparticle. As proof of principle, it was tested for a simple and rapid quantification of TNT in the presence of interferents of the same chemical family. This...

The preparation of a blue-luminescent and photostable organic-inorganic hybrid perovskite with an X-ray powder diffraction spectrum consistent with a two-dimensional inorganic framework is reported. This perovskite can be produced with a high reaction yield and valuable optical properties, such as luminescence quantum yield over 20%, radiative rate...

The addition of Au3+ to spherical amine-capped CdSe@ZnS nanoparticles in toluene at room temperature and under darkness can lead to ternary CdSe@ZnS/Au nanohybrids. We demonstrate that this happens only when the nanoparticles possess a relatively thin ZnS shell, thus showing that thickness plays a key role in gold deposition on the CdSe@ZnS nanopar...

Organometal halide perovskites (hybrid perovskites) contain an anionic metal–halogen-semiconducting framework and charge-compensating organic cations. As hybrid materials, they combine useful properties of both organic and inorganic materials, such as plastic mechanical properties and good electronic mobility related to organic and inorganic materi...

Metal nanoparticles, with a wide range of applications in catalysis and sensing, have structural and electronic properties that differ from those of their bulk macroscopic counterparts. Electrochemical techniques are of particular interest in the study of metal nanoparticles because electrons may undergo quantum confinement effects which are reflec...

Highly luminescent and photostable CH3NH3PbBr3 nanoparticles have been prepared by fine-tuning the molar ratio between CH3NH3Br, PbBr2, a medium-size alkyl-chain ammonium salt, and 1-octadecene. They exhibit a unique photoluminiscence quantum yield (ca. 83%) and average recombination lifetime (ca. 600 ns) in toluene dispersion.

Supplementary

A flexible, highly sensitive sensor of oxygen in non-aqueous solvents is described. It consists of CdSe/ZnS nanoparticles decorated with a considerable number of pyrene units, thus making the formation of the pyrene excimer possible. The emission of the pyrene excimer and that of the nanoparticle are suitably separated from each other and also from...

Chiral quantum dots (QDs), differing in their core or shell size and, consequently, in their optical properties, were synthesized by the treatment of commercially available amine-capped quantum dots with methyl ester N-acetyl-L-cysteine (CysP). Interestingly, their colloidal methanol solutions remain stable for several months. Their NMR and IR spec...

Core-shell (CS) CdSe/ZnS quantum dots (QD) capped with ligands that possess a mercapto or an amino group and a naphthalimide (NI) as chromophore unit, linked by a short ethylene chain (CS@S-NI and CS@H2N-NI, respectively), have been synthesized and fully characterized by infrared and nuclear magnetic resonance spectroscopies, high-resolution transm...

The quenching of pyrene and 1-methylpyrene fluorescence by nitroanilines (NAs), such as 2-, 3-, and 4-nitroaniline (2-NA, 3-NA, and 4-NA, respectively), 4-methyl-3-nitroaniline (4-M-3-NA), 2-methyl-4-nitroaniline (2-M-4-NA), and 4-methyl-3,5-dinitroaniline (4-M-3,5-DNA), are studied in toluene and 1,4-dioxane. Steady-state fluorescence data show th...

Highly fluorescent organogels (QD-organogel), prepared by combining a pseudopeptidic macrocycle and different types of CdSe quantum dots (QDs), have been characterized using a battery of optical and microscopic techniques. The results indicate that the presence of the QDs not only does not disrupt the supramolecular organization of the internal fib...

The high surface-to-volume ratio of nanoparticles has been used to obtain a high local concentration of pyrene units on their periphery, making the formation of both pyrene emissive species possible using amazingly small pyrene concentrations. The sensing properties of model pyrene-functionalized nanoparticles was investigated by using different ni...

Highly fluorescent organic-and water-soluble CdSe/ZnS core-shell quantum dots (QDs) with thiol ligands chemisorbed on the QD surface were synthesized by the replacement of amine ligands by alkyl thiols under very mild conditions. The QDs exhibited an even greater photostability than the initial core-shell amine capped QDs.

Pyrene fluorophores of pyrene-functionalized CdSe quantum dots (QD@Py), as well as alkylpyrene and pyrene itself (Py), undergo fast degradation in aerated chloroform under ultraviolet-A (UV-A, 316<λ<400 nm) illumination. Steady-state fluorescence studies of irradiated chloroform solutions of QD@Py show formation of new bands, red-shifted compared t...

A supramolecular system based on ketoprofen functionalised CdSe/ZnS nanoparticles and pyrene-modified β-CD was prepared and successfully used for molecular sensing of different analytes. In addition, a strategy for the individual recovery of all the components of the sensing assay is reported.

The size of core-shell CdSe/ZnS quantum dots can be decreased by using the combined action of an n,π* aromatic ketone and UVA light. Energy-dispersive X-ray spectroscopy as well as X-ray photoelectron spectroscopy techniques gave information on the photosensitization mechanism and the eventual destiny of Cd(2+) and Se(2-) core ions. Our data suppor...

The present communication reports that while addition of alkyl thiols drastically reduces the fluorescence of CdSe core quantum dots, it actually enhances the emission properties of already highly fluorescent amine-capped CdSe/ ZnS core-shell quantum dots. Résumé : On montre dans ce travail que, alors que l'addition d'alkylthiols diminue d'une faço...

Light-driven catalytic strategies are of great interest for the synthesis of useful products causing minimal environmental impact. Nature provides many examples of systems working in processes activated by light, and understanding them has been and, in the future, will be useful in the design of artificial catalysts.

A photostable dicyanomethylenedihydrofuran fluorophore which contains electron-donating alkoxy groups is described. This chromophore is highly environmentally-sensitive, which is a remarkable property for a fluorescent reporter. Its light excitation also enables, in low viscous solvents, the formation of dark states whose radical or triplet nature...

We discuss the main mechanisms of interaction between quantum dots (QDs) of different types and organic molecules within the framework of the use of photo-physical properties of colloidal semiconductor nanoparticles for sensing organic and biochemical compounds. We reviewed the recent literature in the field to provide a picture of the state of the...

A novel effect of n pi* aromatic ketones on the quantum dots optical properties is reported. By controlling experimental conditions such as time of irradiation, presence of air in the media, hydrogen donor capacity of the solvent, and irradiation wavelength, core and core-shell CdSe QDs can be resized as convenient.

The effect of different amines on the fluorescence of quantum dots has been discussed in the literature but the mechanism involved is not fully understood. We have studied the interaction of core CdSe quantum dots of different sizes and core-shell CdSe quantum dots with tertiary amines, such as aliphatic amines (triethylamine) and bicyclic amines (...

Quenching of the 2-benzoylthiophene pi,pi* triplet, (BT)-B-3*, by phenol yields the corresponding ketyl and phenoxyl radicals. Reaction rates were measured in 10 solvents having a range of hydrogen-bond acceptor strengths (beta(H)(2) values). There appear to be two mechanisms: (i) a bimolecular reaction of (BT)-B-3* with "free" (i.e., not H-bonded)...

The effect of cyclodextrins (CDs) in the excited state proton transfer process of indole compounds has been studied by fluorescence quenching, in acid and alkaline media. The quenching efficiency decreases in the presence of CDs in both media indicating a remarkable protection mediated by CD against external quenchers. An interesting non-linear beh...

(Chemical Equation Presented) Dual function: The potential of aromatic ketones as photocatalysts, acting as triplet-triplet photosensitisers and subsequently, as ground state electron acceptors is shown for the photosensitised oxidative decarboxylation of naproxen (see figure).

The potential performance of Photonic Crystal Fibers (PCF) in the construction of microdevices, particularly sensors, has not been fully explored. One of the principal requirements for new PCF applications is the incorporation of additional functionality. We have explored the possibility of filling the PCF microchannels with liquids containing fluo...

Quenching of quantum dot luminescence by nitroxides shows steep exponential behavior and is dependent on nanoparticle size, being most effective for the smaller particles. The interaction of CdSe nanoparticles with TEMPO (non-binding) and 4-amino-TEMPO (binding) has been examined using fluorescence and electron spin resonance techniques. The data s...

The lowest lying triplet excited states of diaryl ketones are usually long lived and can be photochemically generated with high quantum yields. Hence, compounds of this type are efficient triplet photosensitizers. Three major mechanisms, namely hydrogen abstraction, energy transfer and electron transfer, can be involved in the photosensitized proce...

Experimental evidence is provided for the occurrence of triplet-triplet energy transfer from benzoylthiophene-indole exciplexes to naphthalenes with a remarkable stereodifferentiation; chiral recognition is also observed in the decay of the generated naphthalene triplets.

Quenching of quantum dot luminescence by nitroxides is extremely non-linear and dependent on nanoparticle size, being most effective for the smaller particles; it is proposed to involve an electron exchange mechanism.

Drug-induced photoallergy requires as the first step formation of covalent drug-protein photoadducts. One of the key amino acids involved in this process is tryptophan (Trp). In this context, several diaryl ketones, including 2-benzoylthiophene (BT), [2-(5-benzoyl-5-thienyl)]-2-methylpropanoic methyl ester (TPA methyl ester) and 4-(2-thienylcarbony...

Efficient benzylic radical formation from benzo[d]-1,2-oxaphospholes has demonstrated their suitability as precursors of stabilized C-centered radicals, a property associated with antioxidant potential. A remarkable stereodifferentiation is observed for alkyl- and aryl-substituted derivatives. [reaction: see text]

Experimental evidence has been obtained for the involvement of encounter complexes between both enantiomers of a pi,pi* triplet excited ketone and a chiral phenol or indole. Determination of the pre-equilibrium constants (K(EC)) and the intrinsic decay rate constants (kd) indicates a significant stereodifferentiation in both steps of the quenching...

The effect of hydroxypropyl-β-cyclodextrin (HPβCD, β-cyclodextrin (βCD) derivative) was determined on the fluorescence emission spectra of skatole (3-methylindole, MI) and auxin (indole 3-acetic acid, IA). The experiments were conducted at excitation wavelength (λex)=280nm, in aqueous solutions at different pH values, with and without HPβCD as rece...

The photochemical reaction of Trp and Tyr and related peptides with Suprofen (SUP) as sensitizer in H2O/CH3CN (28:1 v/v) solutions has been studied by time-resolved spectroscopy. The results show that SUP induces oxidation of both Trp and Tyr, as well as intramolecular-ET reactions in the related peptides. The influence of photosensitizer configura...

[reaction: see text] Several benzo[d]-1,2-oxaphosphole 2-oxides were examined as potential precursors of stabilized C-centered radicals. The transient absorption spectra obtained after laser flash photolysis in the presence of di-tert-butyl peroxide showed the features of benzylic radicals with formation and decay kinetics not significantly influen...

Quenching of the excited triplet state of 2-benzoylthiophene (BT) by 3-methylindole (CH3InH) leads to several neutral radicals resulting from formal hydrogen-atom abstraction. The transient absorption spectra of the BT ketyl radical (BTH) and the N-centered (CH3In) radical are directly detected by laser flash photolysis. From the differences betwee...

Laser flash photolysis, density functional theory (DFT) calculations, and product studies have been performed to understand the mechanism of photoreduction of 2-benzoylthiophene (BT) in the presence of phenol or indole. Time-resolved experiments showed that BT ketyl (BTH) and phenoxy (PhO) or indolyl (In) radicals are generated with high rate const...

Several methods are described for the simultaneous determination of binary mixtures of xanthopterin (XAN) and isoxanthopterin (ISO) and of binary mixtures of xanthopterin and biopterin (BIO). The total luminiscence information from each compound has been used to optimize the most adequate analytical signal. A synchronous spectrofluorometric univari...

The effects of native cyclodextrins (alpha, beta or gamma), hydroxypropyl-beta-cyclodextrin, beta-cyclodextrin solubilized in urea, soluble starch and glucose in water solution on the fluorescence behaviour of melatonin (N-acetyl-5-methoxytryptamine) (M) and 5-methoxytryptamine [5-methoxy-3-(2-aminoethyl)indole] (5M) were determined. In addition, t...

The effect of native cyclodextrins (alpha-, beta- or gamma- with six, seven or eight glucose units, respectively), hydroxypropyl-beta-cyclodextrin, beta-cyclodextrin solubilized in urea, soluble starch and glucose in water solution on the fluorescence behaviour of tryptamine [3-(2-aminoethyl)indole] (T) was determined. In addition, the effect of me...