Tryptophanol-derived oxazoloisoindolinone fluorescent probes for cellular localization studies of p53 activators.

The protein p53 is a transcription factor with several key roles in cells, including acting as a tumour suppressor. In most human cancers its tumour suppressor function is inactivated, either through inhibition by negative regulators or by mutation in the TP53 gene. Thus, there is a high interest in developing molecules able to activate p53 tumour suppressor activity.

Curved Nanographenes as Stoppers in a [2]Rotaxane with Two-Photon Excited Emission.

Heptagon-containing distorted nanographenes are used as stoppers for the capping of a [2]rotaxane through a Michael-type addition reaction to vinyl sulfone groups. These curved aromatics are bulky enough to prevent the disassembly of the rotaxane but also give emissive and nonlinear (two-photon absorption and emission) optical properties to the structure.

Atomically Precise Distorted Nanographenes: The Effect of Different Edge Functionalization on the Photophysical Properties down to the Femtosecond Scale.

Nanographenes (NGs) have been attracting widespread interest since they combine peculiar properties of graphene with molecular features, such as bright visible photoluminescence. However, our understanding of the fundamental properties of NGs is still hampered by the high degree of heterogeneity usually characterizing most of these materials. In this context, NGs obtained by atomically precise synthesis routes represent optimal benchmarks to unambiguously relate their properties to well-defined structures.

Safety assessment of new nanodiamonds@corrole hybrids addressed by the response of RAW-264.7 macrophages.

Safety assessment of carbon nanomaterials is of paramount importance since they are on the frontline for applications in sensing, bioimaging and drug delivery. The biocompatibility and safety of functionalized nanodiamonds (NDs) are here addressed through the study of the pro-inflammatory response of RAW-264.7 macrophages exposed to new nanodiamonds@corrole hybrids.

Highly contorted superhelicene hits near-infrared circularly polarized luminescence.

Herein we describe a novel superhelicene structure consisting of three hexa--hexabenzocoronene (HBC) units arranged in a helical geometry and creating two carbo[5]helicenes and a carbo[7]helicene. The central HBC bears a tropone moiety, which induces a saddle-helix hybrid geometry into the 3D structure of the prepared nanographene. The introduction of multiple helicenes and the position of the tropone unit trigger near-infrared circularly polarized luminescence (NIR-CPL, up to 850 nm, | | = 3.

Graphene Quantum Dots and Phthalocyanines Turn-OFF-ON Photoluminescence Nanosensor for ds-DNA.

Supramolecular hybrids of graphene quantum dots (GQDs) and phthalocyanine (Pc) dyes were studied as turn-OFF-ON photoluminescence nanosensors for detection of ds-DNA. Pcs with four (Pc4) and eight (Pc8) positive charges were selected to interact with negatively charged GQDs. The photoluminescence of the GQDs was quenched upon interaction with the Pcs, due to the formation of non-emissive complexes.

Combining metal nanoclusters and carbon nanomaterials: Opportunities and challenges in advanced nanohybrids.

The development of functional materials with uniquely advanced properties lies at the core of nanoscience and nanotechnology. From the myriad possible combinations of organic and/or inorganic blocks, hybrids combining metal nanoclusters and carbon nanomaterials have emerged as highly attractive colloidal materials for imaging, sensing (optical and electrochemical) and catalysis, among other applications. While the metal nanoclusters provide extraordinary luminescent and electronic properties, the carbon nanomaterials (of zero, one or two dimensions) convey versatility, as well as unique interfacial, electronic, thermal, optical, and mechanical properties, which altogether can be put to use for the desired application.

A Fluorescent Nanosensor for Silver (Ag) and Mercury (Hg) Ions Using Eu (III)-Doped Carbon Dots.

Carbon dots doped with Eu ions (Eu-Cdots) were prepared by a hydrothermal treatment, using citric acid and urea as precursors and Eu (NO) as a europium source. The Eu ions are strongly coordinated with the carboxylate groups at the surface of the Cdots and incorporated within the nanographene network in the carbon core. Vibrational spectroscopy provides evidence of such interaction with identification of bands assigned to the stretching of the Eu-O bond.

Two-photon activated precision molecular photosensitizer targeting mitochondria.

Mitochondria metabolism is an emergent target for the development of novel anticancer agents. It is amply recognized that strategies that allow for modulation of mitochondrial function in specific cell populations need to be developed for the therapeutic potential of mitochondria-targeting agents to become a reality in the clinic. In this work, we report dipolar and quadrupolar quinolizinium and benzimidazolium cations that show mitochondria targeting ability and localized light-induced mitochondria damage in live animal cells.

Reflectance Confocal Microscopy: A Powerful Tool for Large Scale Characterization of Ordered/Disordered Morphology in Colloidal Photonic Structures.

The development of appropriate methods to correlate the structure and optical properties of colloidal photonic structures is still a challenge. Structural information is mostly obtained by electron, X-ray, or optical microscopy methods and X-ray diffraction, while bulk spectroscopic methods and low resolution bright-field microscopy are used for optical characterization. Here, we describe the use of reflectance confocal microscopy as a simple and intuitive technique to provide a direct correlation between the ordered/disordered structural morphology of colloidal crystals and glasses, and their corresponding optical properties.

Investigation of the mechanical properties and biocompatibility of planar and electrospun alkene-styrene copolymers against P(VDF-TrFE) and porcine skin: Potential use as second skin substrates.

Elastomers have been used in a variety of biomedical fields, including tissue engineering, soft robotics, prostheses, and cosmetics. Elastomers used for skin grafting scaffolds tend to be biodegradable, but other applications require perdurable elastomers. Advances in perdurable elastomers would allow for the development of a range of substrates useful in the creation of joint prostheses, chronic neural electrodes, implantables, and wearables.

Two-Photon Absorption Enhancement by the Inclusion of a Tropone Ring in Distorted Nanographene Ribbons.

A new family of distorted ribbon-shaped nanographenes was designed, synthesized, and their optical and electrochemical properties were evaluated, pointing out an unprecedented correlation between their structural characteristics and the two-photon absorption (TPA) responses and electrochemical band gaps. Three nanographene ribbons have been prepared: a seven-membered-ring-containing nanographene presenting a tropone moiety at the edge, its full-carbon analogue, and a purely hexagonal one. We have found that the TPA cross-sections and the electrochemical band gaps of the seven-membered-ring-containing compounds are higher and lower, respectively, than those of the fully hexagonal polycyclic aromatic hydrocarbon (PAH).

A Triskelion-Shaped Saddle-Helix Hybrid Nanographene.

A unique rippled nanographene consisting of 52 fused rings is presented in which six out-of-plane motifs are fully fused into a triangular aromatic surface with a size of approximately 2.5 nm. Three units of an unprecedented fully lateral π-extended octabenzo[5]helicene together with three units of saddle-shaped heptagonal rings are combined in a single structure, leading to a well-soluble warped nanographene.

Undecabenzo[7]superhelicene: A Helical Nanographene Ribbon as a Circularly Polarized Luminescence Emitter.

The synthesis and characterization of an enantiopure superhelicene nanographene is reported in which two saddle-shaped and one planar hexabenzocoronene (HBC) units are arranged in a helicoidal shape to form an undecabenzo[7]carbohelicene. The described compound is the first fully π-extended [7]helicene. Racemic resolution of the helical nanographene permitted analysis of the chiroptical properties and revealed dissymmetry factors in the range of 2×10 both in the absorption and in the emission measurements.

Selective two-photon absorption in carbon dots: a piece of the photoluminescence emission puzzle.

Carbon nanodots (Cdots) are now emerging as promising nonlinear fluorophores for applications in biological environments. A thorough and systematic approach to the two-photon induced emission of Cdots that could provide design guidelines to control their nonlinear emission properties is still missing. In this work, we address the nonlinear optical spectroscopy of Cdots prepared by controlled chemical cutting of graphene oxide (GO).

Enantiopure distorted ribbon-shaped nanographene combining two-photon absorption-based upconversion and circularly polarized luminescence.

Herein we describe a distorted ribbon-shaped nanographene exhibiting unprecedented combination of optical properties in graphene-related materials, namely upconversion based on two-photon absorption (TPA-UC) together with circularly polarized luminescence (CPL). The compound is a graphene molecule of 2 nm length and 1 nm width with edge defects that promote the distortion of the otherwise planar lattice. The edge defects are an aromatic saddle-shaped ketone unit and a [5]carbohelicene moiety.

Porphyrin-Oligopyridine Triads: Synthesis and Optical Properties.

The synthesis of two triads with two porphyrinyl units linked by oligopyridine derivatives and a new β-functionalized porphyrin-dihydroazepine is described. One of the porphyrin-oligopyridine triads has a quinquepyridine unit connecting the porphyrins β-pyrrolic positions, while the other one has an asymmetric quaterpyridine with one of the pyridines fused to the porphyrin. All compounds have fluorescence emission quantum yields in the range of meso-tetraphenylporphyrin (16-22%).

Aggregation-induced emission of [3]cumulenes functionalized with heptagon-containing polyphenylenes.

Turning on the fluorescence of [3]cumulenes: we report the luminescence at room temperature upon aggregation of [3]cumulenes functionalized with propeller-like heptagon-containing polyphenylenes. These endgroups turn on the emission of a [3]cumulene by steric protection and restriction of their intramolecular rotations in the aggregates.

Cryptolepine and quindoline: understanding their photophysics.

Quindoline (QUIND, indolo[3,2-b]quinoline) and cryptolepine (CRYPT, 5-methyl-10H-indolo[3,2-b]quinoline) together with their corresponding derivatives have been studied for decades due to their important biological activity against diseases like malaria. The biological activity of drugs is routinely investigated using fluorescence based methods. However, recent reports show that the photophysics of CRYPT and its analogues is not yet understood.

Impact of Molecular Organization on Exciton Diffusion in Photosensitive Single-Crystal Halogenated Perylenediimides Charge Transfer Interfaces.

The efficiency of organic photodetectors and optoelectronic devices is strongly limited by exciton diffusion, in particular for acceptor materials. Although mechanisms for exciton diffusion are well established, their correlation to molecular organization in real systems has received far less attention. In this report, organic single-crystals interfaces were probed with wavelength-dependent photocurrent spectroscopy and their crystal structure resolved using X-ray diffraction.

Effect of Molecular Stacking on Exciton Diffusion in Crystalline Organic Semiconductors.

Exciton diffusion is at the heart of most organic optoelectronic devices' operation, and it is currently the most limiting factor to their achieving high efficiency. It is deeply related to molecular organization, as it depends on intermolecular distances and orbital overlap. However, there is no clear guideline for how to improve exciton diffusion with regard to molecular design and structure.

Role of vibrational dynamics in electronic relaxation of Cr(acac)₃.

Ultrafast energy relaxation of Cr(acac)3 dissolved in tetrachloroethylene (TCE) is studied by time-resolved infrared (TRIR) spectroscopy by using electronic and vibrational excitation. After electronic excitation at 400 or 345 nm, the ground state recovers in two time scales: 15 ps (major pathway) and 800 ps (minor pathway), corresponding to fast electronic transition to the ground state and intermediate trapping on the long-lived (2)E state followed by intersystem crossing (ISC) to the ground state. The quantum yield for the fast recovery of the ground state depends on the excitation wavelength, being higher for 345 nm.

Nonlinear emission of quinolizinium-based dyes with application in fluorescence lifetime imaging.

Charged molecules based on the quinolizinum cation have potential applications as labels in fluorescence imaging in biological media under nonlinear excitation. A systematic study of the linear and nonlinear photophysics of derivatives of the quinolizinum cation substituted by either dimethylaniline or methoxyphenyl electron donors is performed. The effects of donor strength, conjugation length, and symmetry in the two-photon emission efficiency are analyzed in detail.

"Click and go": simple and fast folic acid conjugation.

Folic acid targeting by functionalization of the terminal γ-carboxylic acid is one of the most important strategies to selectively deliver chemotherapeutics and dyes to cancer cells which overexpress folate receptors. However, conjugation of folic acid is limited by its unique solubility and by selectivity issues imposing the need for expensive preparative reverse-phase chromatographic purification to isolate γ-folate conjugates. Herein is provided a novel synthetic tool for the synthesis of new folic acid conjugates with excellent γ-purity based on strain-promoted alkyne-azide cycloadditions with a γ-folate-cyclooctyne conjugate 3.

Excited-state proton transfer of fluorescein anion as an ionic liquid component.

Fluorescent ionic liquids (FILs) incorporating the fluorescein anion have been prepared by anion exchange of the parent quaternary ammonium chloride (Quat(+)Cl(-)) ionic liquid. By controlling the molar ratio of fluorescein to Quat(+)Cl(-), ionic liquids incorporating different prototropic forms of fluorescein were prepared. The 1:1 molar ratio ionic liquid (FIL1) is essentially composed of monoanionic fluorescein, while dianionic fluorecein is predominant in the FIL with a 1:2 molar ratio (FIL2).