Photoacoustic signal generation by metal nanoparticles relies on the efficient conversion of light to heat, its transfer environment, and production pressure transients. In this study we demonstrate that a dielectric shell has strong influence amplitude generated photoacoustic silica-coated gold nanorods same optical density are capable producing about 3-fold higher signals than without silica coating. Spectrophotometry measurements finite difference time domain (FDTD) analysis before after...

2,5-Disubstituted oxazoles are synthesized from the corresponding propargylcarboxamides under mild reaction conditions via homogeneous catalysis by AuCl3. While monitoring conversion 1H NMR spectroscopy, an intermediate 5-methylene-4,5-dihydrooxazole can be observed and accumulated up to 95%, being first direct catalytic preparative access such alkylidene oxazolines. The was fully characterized trapped at −25 °C for several weeks. Deuteration experiments show a stereospecific mode of two...

Photothermal stability and, therefore, consistency of both optical absorption and photoacoustic response the plasmonic nanoabsorbers is critical for successful image-guided photothermal therapy.In this study, silica-coated gold nanorods were developed as a multifunctional molecular imaging therapeutic agent suitable therapy.The properties under intense irradiation with nanosecond laser pulses investigated by UV-Vis spectroscopy transmission electron microscopy.Silica-coated showed increased...

Abstract The substrate scope, the mechanistic aspects of gold‐catalyzed oxazole synthesis, and substrates with different aliphatic, aromatic, functional groups in side chain were investigated. Even molecules several propargyl amide could easily be converted, delivering di‐ trioxazoles interesting optical properties. Furthermore, scope gold(I)‐catalyzed alkylidene synthesis was Further functionalizations these isolable intermediates developed chelate ligands can obtained. use Barluenga’s...

An elusive intermediate in the gold-catalyzed phenol synthesis was elucidated by modifying energy profile of this process. Thus, use a ligand based on 2-hydroxymethylpyridine enabled first observation arene oxide, which can be enriched to account for up 80 % material reaction mixture at room temperature (see scheme).

Reaction of the cationic binuclear gold(I) complex [(Ph3PAu)2Cl]BF4 with ω-alkynylfurans furnished phenols as major product and anellated furans side-products. The analogous trimesitylphosphane [(Mes3PAu)2Cl]BF4 selectively afforded only phenols. latter catalyst then enabled first intermolecular gold-catalyzed phenol synthesis.

Different furans containing an ynamide or alkynyl ether moiety in the side chain were prepared. The gold-catalyzed transformation of these compounds delivered dihydroindole, dihydrobenzofuran, chroman, and tetrahydroquinoline derivatives at room temperature through very fast reactions. Furthermore, stabilizing effect heteroatom directly attached to intermediate arene oxides led highly selective reactions, even case only mono-substituted furans, which is quite different from previous results...

The second phase of the gold-catalyzed phenol synthesis, ring opening intermediate arene oxide, follows general acid catalysis. product selectivity is determined by substrate only and can be explained stability arenium ions. Thus, even remote substitutents used to control chemoselectivity overall reaction electronic influences their influence stronger than steric neighboring substituents. This supported quantum chemical calculations intermediates. lack exchange deuterium labels excludes...

Different diyne-diols composed of two terminal homopropargylic alcohol groups were prepared by bi-directional synthesis. Subjection the syn diastereomers to NAC-gold catalysts (NAC=nitrogen acyclic carbene) in presence external nucleophiles such as water or anilines provided substituted and highly rigid heterocyclic cages. The corresponding anti disastereomers polymerised. An intermediate reactions could be isolated even characterised crystal structure analysis. Overall, eight new bonds are...

Nanoparticle-augmented photoacoustics is an emerging technique for molecular imaging. This study investigates the fundamental process of photoacoustic signal generation by plasmonic nanoparticles suspended in a weakly absorbing fluid. The gold nanospheres with varying silica shell thicknesses shown to be dominated heat transfer between and surrounding environment. Detailed facts importance specialist readers are published as "Supporting Information". Such documents peer-reviewed, but not...

We have investigated the crystal field splitting in archetypal lanthanide-based single-ion magnets and related complexes (NBu4)+[LnPc2]−·2dmf (Ln = Dy, Ho, Er; dmf N,N-dimethylformamide) by means of far infrared inelastic neutron scattering spectroscopies. In each case, we found several features corresponding to direct transitions within ground multiplet. The observation three independent peaks holmium derivative enabled us derive parameters. addition, carried out CASSCF calculations. show...

The electronic structure of a novel lanthanide-based single-ion magnet, {C(NH2)3}5[Er(CO3)4]·11H2O, was comprehensively studied by means large number different spectroscopic techniques, including far-infrared, optical, and magnetic resonance spectroscopies. A thorough analysis, based on crystal field theory, allowed an unambiguous determination all relevant free ion parameters. We show that inclusion methods sensitive to the nature lowest-energy states is essential arrive at correct...

Abstract A series of heteroleptic copper(I) photosensitizers the type [(P^P)Cu(N^N)] + with an extended π‐system in backbone diimine ligand has been prepared. The structures all complexes are completely characterized by NMR spectroscopy, mass spectrometry, and X‐ray crystallography. These novel were assessed respect to photocatalytic reduction protons presence triethylamine [Fe 3 (CO) 12 ]. Although solid‐state computational results show no significant impact π‐extension on structural...

Abstract Molecular photoacoustic imaging has shown great potential in medical applications; its sensitivity is normally pico-to-micro-molar range, dependent on exogenous agents. However, tissue can produce strong background signals, which mask the signals from agents, resulting orders of magnitude reduction. As such, an elaborate spectral scan often required to spectrally un-mix unwanted signals. Here we show a new single-wavelength dynamic contrast-enhanced technique by employing...

The magnetic properties of the title complexes were studied by EPR spectroscopy, magnetometry and<italic>ab initio</italic>calculations.

Abstract Several propargylic trichloroacetimidates have been prepared and their reactions with gold catalysts studied. Only the propargyl 1‐methylpropargyl substituent was a selective cyclization observed; gold(III) chloride in acetonitrile only product of fast hydroamination to 4‐methylene‐4,5‐dihydrooxazoles obtained, chloroform slower subsequent aromatization could not be prevented which delivered oxazoles after long reaction times. Up 3333 turnovers reached. With gold(I) or...

Abstract Different furyl‐substituted ( Z )‐dehydroamino acid derivatives were hydrogenated with the rhodium/Mandyphos(OMe)‐system to give enantiomeric excesses between 80 and 98 %. The absolute configuration of newly formed stereogenic center was determined by anomalous diffraction be R . These chiral furyl alanines transferred into 8‐hydroxytetrahydroisoquinolines employing gold‐catalyzed arene synthesis as key step. During latter reaction sequence, also including either a propargylation or...

Changing tracks: By the use of alkynyl ethers as directing elements, furan-yne cyclization enters a new reaction pathway. Instead phenols, tetracycles containing two heteroatoms and stereocenters are formed (see scheme).

Cooperative activation by a soft bimetallic catalyst, hard Brønsted acid, and base has allowed the formation of highly enantioenriched, diastereomerically pure masked α-amino acids with adjacent quaternary tertiary stereocenters in single reaction starting from racemic N-benzoylated amino acids. The products can, for example, be used to prepare bicyclic dipeptides.

Abstract The synthesis of disubstituted chiral diene ligands (3a R ,6a )‐ and S 10 with a pentalene backbone from the corresponding bicyclo[3.3.0]octa‐1,4‐diones 7 is described. latter were accessible by enzymatic resolution racemic diol rac ‐ 5 subsequent Swern oxidation. efficiency in rhodium‐catalyzed 1,4‐addition arylboronic acids 12 to cyclic acyclic enones 11 15 could be demonstrated. In case enantiomeric diphenyldienes 10a more selective than dibenzyldiene 10b . When employed this...

Six different N-alkynyl carbamates containing Boc groups were prepared. Their gold(I)-catalyzed cyclization to ­oxazolinones proceeded radily at room temperature or even lower temperatures.

The effect of different substituents, such as bromo, chloromethyl, hydroxymethyl, formyl, acetyl, carboxy, and acylated hydroxymethyl ammonium groups, on the furan ring substrates in gold-catalyzed phenol synthesis has been investigated. was also replaced by heterocycles, pyrroles, thiophenes, oxazoles, a 2,4-dimethoxyphenyl group; gold catalysis then delivered no phenols, but occasionally other products were obtained. [Ru(3)(CO)(12)] catalyzed conversion 1 at low rate, [Os(3)(CO)(12)]...

We synthesized the first N-heterocyclic carbene (NHC) complexes of Schrock's molybdenum imido alkylidene bis(triflate) complexes. Unlike existing complexes, novel 16-electron represent metathesis active, functional-group-tolerant catalysts. Single-crystal X-ray structures two representatives this class Schrock catalysts are presented and reactivity is discussed in view their structural peculiarities. In presence monomer (substrate), these form cationic species can be employed ring-closing...

The synthesis, structure, and olefin metathesis activity of the first neutral cationic W-oxo-alkylidene-N-heterocyclic carbene (NHC) catalysts are reported. Neutral W-oxo-alkylidene-NHC can be prepared in up to 90% isolated yield. Depending on ligands used, they possess either an octahedral (Oh) or trigonal bipyramidal ligand sphere. They activated with excess AlCl3 form metathesis-active W-complexes; however, these readily convert into chloro-complexes. Well-defined, stable species by...

The direct asymmetric conjugate addition of α-cyanoacetates to enones generating densely functionalized α-amino acid precursors with adjacent quaternary and tertiary stereocenters is described comparing mono- bis-palladacycle catalysts. This edge article features the complementary value bimetallic catalysis in a case study using related catalyst systems. Different major diastereomers 1,4-addition products are formed by use planar chiral systems provide access epimeric amino derivatives. Both...