Detailed understanding of the interaction between ac hiral molecule and an oble metal surface is essential to rationalizea nd advance interfacial self-assembly of amino acids and metal-mediated anchoring of proteins.H ere we demonstrate that individual Au@Agc ore-shell nanocuboids can serve as ap lasmonic reporter of an extended helical network formed among chemisorbed cysteine molecules, through generating an interband absorption enhanced, Agsurface-exclusive circular dichroism (CD) band in the UV region. The observed unusual, strong CD response in the hybrid Au@Ag-cysteine system can be used to probe in real time conformational evolution and structural rearrangement of biomolecules in general and also monitor the interfacial interaction between ametal surface and an adsorbed molecule, opening up the possibility of using Ag nanostructures as promising stereochemically attuned nanosensors.
Acting as an extracellular matrix protein receptor, V 3 integrin becomes an appealing target for photodynamic therapy of bladder cancer. Here, specific V 3 -integrin-targeting porphyrinato-gadolinium complexes (Gd-PEG-R n ) are demonstrated as off-on theranostic agents, where R n are specific peptides. Among them, Gd-PEG-R 3 shows both impressive phototherapeutic index and robust in vivo magnetic resonance imaging (MRI) signal enhancement. Significant selectivity of Gd-PEG-R 3 is proven by its high V 3 integrin binding affinity in positive bladder cancer cells. All these findings support Gd-PEG-R 3 as a promising bi-functional medical agent with both MRI contrasting ability and photodynamic therapeutic potential for curing bladder cancer.Despite photodynamic therapy (PDT) providing an efficient strategy in medical treatment, [1] scientists are keen to progress on from single-function PDT agents to more elaborate drugs. The term "theranostic" characterizes a class of multifunctional compounds with both therapeutic and diagnostic functions. In particular, the combination of PDT with magnetic resonance imaging (MRI) seems to have promising potential, especially for those working under two-photon excitation. [2,3] With bifunctional drugs attracting more attention, the balance between
Photoexcitation at a certain wavelength in the near-infrared (NIR) region followed by luminescence at a shorter wavelength in the visible domain is called near-infrared-to-visible photon upconversion. This is a rather unusual process as lowenergy photons are "converted" into higher energy photons: two or three photons of NIR light are required to generate one photon of visible light.[1] Nonlinear optics (NLO) is another mechanism that can lead to the generation of light at a frequency that is either twice or integral-multiples of the incident light.[2] The phenomena of two-or three-photon upconversion, and second or third harmonic generation (SHG or THG) on organic materials have received considerable attention since fluorescence detection became popular in applications such as photodynamic therapy, optical data storage, and microfabrication. [3] Multiphoton excitation allows molecules that typically absorb in the UV region to be excited with red or NIR light. The photoluminescence processes from organolanthanide complexes are usually induced by an organic chromophoric ligand that absorbs incident light and transfers its resultant excitation energy to the lanthanide ion.[4] Until now, only a few multiphoton processes in organolanthanide complexes have been observed owing to the limitations of experimental measurements.[5] Although there have been reports on lanthanide complexes that display second harmonic generation, these have been limited and focused only on glassy doped lanthanide materials.[6] In recent years, our group [7] and others [8] have investigated several high-order multiphoton processes from organic ligands and metal complexes. Herein we report, to the best of our knowledge, the first observation of rare multiphoton upconversion emission from a lanthanide complex as well as SHG and THG transmission phenomena, which occur simultaneously from the same excitation source in the IR region at l % 1.26 and 1.34 mm.The N-tripodal ligand L was treated with terbium nitrate to give the complex [Tb(L)(NO 3 ) 3 ] (1, see Figure 1), which is thermally stable up to 300 8C, as shown by thermogravimetric analysis (see Supporting Information). Single crystals of 1 were isolated through the slow evaporation of a solution of 1 in THF/MeCN at room temperature over a few days. The crystal structure of 1 was determined by X-ray crystallography and is shown in Figure 2. The coordination geometry of the metal center in 1 can be described as a tricapped trigonal prism, in which each Tb 3+ ion is coordinated by three carbonyl (amide) groups from three separate but identical tripodal ligands, and doubly coordinated by three nitrate ions. Upon complexation, the tripodal ligand adopts a polymetallic dendritic form, as the branches contain oxygen groups for binding with lanthanide ions. The ensemble of the tripodal ligand and its connectivity with the lanthanide ion, which itself is preorganized as a result of its coordination to three chromophores, forms a metallodendrimer. The metal takes on a "metal as ligand, metal as co...
Eight makes a happy Ho(l)me: The versatile octadentate TIAM ligand forms lanthanide complexes (Ln=Sm, Eu, Tb, Dy, Ho) with high quantum yields in water. This ligand is an efficient sensitizer, and also shields the metal center from solvent quenching, as shown by an X‐ray diffraction study of the Ho complex.
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