1,720,979 research outputs found
A prototype for the chemosensing ofBa2+ based on self-assemblingfluorescence enhancement
No full textBarium ion can be revealed at the micromolar concentration level by the blue-green fluorescence which arises upon the self-assembling
process involving the metal ion and a bis-15-crown-5-naphthalene-diimide derivative
Metal-Induced Assembling/Disassembling of Fluorescent Naphthalenediimide Derivatives Signalled by Excimer Emission
No full textExcimer emission induced by metal ion coordination in 1,8-naphthalimide-tethered iminopyridine ligands
No full textFluorogenic Detection of Sulfite in Water by Using Copper(II) Azacyclam Complexes
Full text linkCopper(II) azacyclam complexes (azacyclam = 1,3,5,8,12-pentaazacyclotetradecane) contain- ing naphthyl or dansyl subunits can be prepared by template synthesis involving proper sulfonamide derivatives as locking fragments. The macrocyclic complexes are very poorly emissive due to the fluorescence-quenching behavior displayed by Cu2+ ions. However, the fluorescence can be recovered as a result of the decomposition of the complexes, which induces the release of free light-emitting subunits to the solution. This reaction takes place very slowly in neutral water but its rate is increased by the presence of sulfite. Therefore, [Cu(azacyclam)]2+ derivatives have been investigated as simple chemical probes for the fluorogenic detection of sulfite both on laboratory and real samples. Prelim- inary tests performed on samples of white wine provided sulfite concentration values that are in agreement with those obtained by a standard analytical method
Steric hindrance in the on-surface synthesis of diethynyl-linked anthracene polymers
Full text linkHybrid sp-sp2 structures can be efficiently obtained on metal substrates via
on-surface synthesis. The choice of both the precursor and of the substrate
impacts on the effectiveness of the process and the stability of the formed
structures. Here we demonstrate that using anthracene-based molecules as
precursor, the formation on Au(111) of polymers hosting sp carbon chains is
affected by the steric hindrance between aromatic groups. In particular, by
scanning tunneling microscopy and density functional theory calculations we
show that the de-metalation of organometallic structures induces a lateral
separation of adjacent polymers preventing the formation of ordered domains
Uncommon Optical Properties and Silver-Responsive Turn-Off/On Luminescence in a Pt(II) Heteroleptic Dithiolene Complex
Full text linkComplex [Pt(iPr2 pipdt)(Quinoxdt)] (iPr2 pipdt=1,4-diisopropyl-piperazine-2,3-dithione; Quinoxdt=[1,4]dithiino[2,3-b]quinoxaline-2,3-dithiolate) exhibits a remarkable green emission at 570 nm (room temperature), which is above the lowest excited state. The complex is characterized by negative solvatochromism as well as a high second-order polarizability. Addition of AgI ions induces 1) hypsochromic shift of the lowest frequencies and 2) reversible quenching of luminescence. The corresponding Ni and Pd complexes have also been prepared and investigated to assist interpretation of optical properties within the triad. Computational studies based on DFT and time-dependent DFT highlight the electronic properties of [Pt(iPr2 pipdt)(Quinoxdt)]. The preferential site of interaction between the Pt complex and incoming AgI is evidenced by the shape of the Fukui functions, pointing to the thiolic sulfur and platinum atoms as the most reactive sites towards a soft cation. Calculated optical properties are in agreement with experimental findings. This study sheds light on the structure-property relationship for this class of compounds
Driving Organic Nanocrystals Dissolution Through Electrochemistry
Full text linkWe have recently discussed how organic nanocrystal dissolution appears in different morphologies and the role of the solution pH in the crystal detriment process. We also highlighted the role of the local molecular chemistry in porphyrin nanocrystals having comparable structures: in water-based acid solutions, protonation of free-base porphyrin molecules is the driving force for crystal dissolution, whereas metal (ZnII) porphyrin nanocrystals remain unperturbed. However, all porphyrin types, having an electron rich π-structure, can be electrochemically oxidized. In this scenario, a key question is: does electrochemistry represent a viable strategy to drive the dissolution of both free-base and metal porphyrin nanocrystals?
In this work, by exploiting electrochemical atomic force microscopy (EC-AFM), we monitor in situ and in real time the dissolution of both free-base and metal porphyrin nanocrystals, as soon as molecules reach the oxidation potential, showing different regimes according to the applied EC potential
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