Aromatic Fused [30] Heteroannulenes with NIR Absorption and NIR Emission: Synthesis,Characterization, and Excited‐State Dynamics

Two hitherto unknown planar aromatic [30] fused heterocyclic macrocycles (1.1.0.1.1.0), with NIR absorption in free‐base form and protonation‐induced enhanced NIR emission, have been synthesized from easy to make precursors. The induced correspondence of fusion on the macrocyclic structure, electronic absorption, and emission spectra have been highlighted.     

Classification of biodiesel using NIR spectrometry and multivariate techniques

This article describes the classification of biodiesel samples using NIR spectroscopy and chemometric techniques. A total of 108 spectra of biodiesel samples were taken (being three samples each of four types of oil, cottonseed, sunflower, soybean and canola), from nine manufacturers. The measurements for each of the three samples were in the spectral region between 12,500 and 4000 cm⁻¹. The data were preprocessed by selecting a spectral range of 5000-4500 cm⁻¹, and then a Savitzky-Golay second-order polynomial was used with 21 data points to obtain second derivative spectra. Characterization of the biodiesel was done using chemometric models based on hierarchical cluster analysis (HCA), principal component analysis (PCA) and soft independent modeling of class analogy (SIMCA) elaborated for each group of biodiesel samples (cotton, sunflower, soybean and canola). For the HCA and PCA, the formation of clusters for each group of biodiesel was observed, and SIMCA models were built using 18 spectral measurements for each type of biodiesel (training set), and nine spectral measurements to construct a classification set (except for the canola oil which used eight spectra). The SIMCA classifications obtained 100% accurate identifications. Using this strategy, it was feasible to classify biodiesel quickly and nondestructively without the need for various analytical determinations.     

NIR light-responsive nanocarriers for controlled release

The near-infrared (NIR) light in the wavelength range of 780−1700 nm is regarded as transparency therapeutic window for light-activated delivery system in vivo due to the deep tissue penetration and minimum cellular damage of it. Numerous reports about NIR light-sensitive nanocarriers have emerged in the past few years. Here, strategies for the design and fabrication of nanocarriers for NIR light-controlled release are reviewed, which are based on three triggering mechanisms: (1) photoreactions of chromophores, including NIR light-induced photoreactions and upconversion nanoparticles (UCNPs)-mediated photochemical reactions; (2) photothermal effect, triggered by inorganic or organic photothermal conversion agents (PCAs) with the excitation of NIR light; (3) photo-oxidation, induced by reactive oxygen species (ROS) generated by photosensitizers under NIR light radiation. Finally, the challenges and perspectives of NIR light-sensitive nanocarriers for future development are given.     

Fluorescent Phthalocyanine-Encapsulated Bovine Serum Albumin Nanoparticles: Their Deployment as Therapeutic Agents in the NIR Region

In recent times, researchers have aimed for new strategies to combat cancer by the implementation of nanotechnologies in biomedical applications. This work focuses on developing protein-based nanoparticles loaded with a newly synthesized NIR emitting and absorbing phthalocyanine dye, with photodynamic and photothermal properties. More precisely, we synthesized highly reproducible bovine serum albumin-based nanoparticles (75% particle yield) through a two-step protocol and successfully encapsulated the NIR active photosensitizer agent, achieving a good loading efficiency of 91%. Making use of molecular docking simulations, we confirm that the NIR photosensitizer is well protected within the nanoparticles, docked in site I of the albumin molecule. Encouraging results were obtained for our nanoparticles towards biomedical use, thanks to their negatively charged surface (−13.6 ± 0.5 mV) and hydrodynamic diameter (25.06 ± 0.62 nm), favorable for benefitting from the enhanced permeability and retention effect; moreover, the MTT viability assay upholds the good biocompatibility of our NIR active nanoparticles. Finally, upon irradiation with an NIR 785 nm laser, the dual phototherapeutic effect of our NIR fluorescent nanoparticles was highlighted by their excellent light-to-heat conversion performance (photothermal conversion efficiency 20%) and good photothermal and size stability, supporting their further implementation as fluorescent therapeutic agents in biomedical applications.     

1，2-环己二胺缩邻香兰素单核与四核镱稀土配合物的近红外性质

通过配体1,2-环己二胺缩邻香兰素（H2L）和不同的镱盐反应,合成了4个镱稀土配合物[Yb（H₂L）₂]（ClO₄）₃·2CH₃OH·H₂O（1）,[Yb₄（L）₄（NO₃）₂（H₂O）₂]（PF₆）₂·4CH₃CN（2）,[Yb₄（L）₄（H₂O）₂Cl2]（PF₆）₂·2CH₂Cl₂·2H₂O（3）和[Yb₄（L）₄（NO₃）₂（H₂O）₂][Yb（NO₃）₃（H₂O）₂（CH₃OH）]（NO₃）₂·4CH₂Cl₂·6CH₃OH（4）。X射线单晶衍射分析表明配合物1为零维的单核结构,配合物2~4均为四核结构。研究了4个配合物的近红外发光性能。     

1,2-环己二胺缩邻香兰素单核与四核镱稀土配合物的近红外性质

通过配体1,2-环己二胺缩邻香兰素（H₂L）和不同的镱盐反应,合成了4个镱稀土配合物[Yb（H₂L）₂]（ClO₄）₃·2CH₃OH·H₂O（1）,[Yb₄（L）₄（NO₃）₂（H₂O）₂]（PF₆）₂·4CH₃CN（2）,[Yb₄（L）₄（H₂O）₂Cl₂]（PF₆）₂·2CH₂Cl₂·2H₂O（3）和[Yb₄（L）₄（NO₃）₂（H₂O）₂][Yb（NO₃）₃（H₂O）₂（CH₃OH）]（NO₃）₂ ·4CH₂Cl₂·6CH₃OH（4）。X射线单晶衍射分析表明配合物1为零维的单核结构,配合物2~4均为四核结构。研究了4个配合物的近红外发光性能。     

乙醇混合燃料近红外定量分析

采用近红外光谱(NIR)透射法对乙醇混合燃料各成分进行定量分析；其中乙醇体积分数为84．5％～98．2％，汽油体积分数0～15％；通过偏最小二乘法(PLS)建立模型，乙醇含量NIR模型校正集测定系数(R^2)为0．9969，模型校正集标准差(SEE)和预测集标准差(SEP)分别为0．23和0．38，汽油含量NIR模型校正集测定系数为0．9939，模型校正集标准差和预测集标准差分别为0．38和0．39，对含量较小的干扰物质丙酮预测结果也理想；近红外和多元校正技术可作为乙醇混合燃料中成分含量测定简单、快速方法之一。     

鲜烟叶中质体色素的近红外分析研究

本文采用近红外漫反射光谱技术和偏最小二乘法,建立了质体色素(叶绿素和类胡萝卜素)中两种组分的数学模型,并对所建立的数学模型进行了优化和验证。结果表明,用近红外定量分析鲜烟叶中质体色素的含量是完全可行的。     

Tailoring noise frequency spectrum to improve NIR determinations

Near infrared spectroscopy (NIR) contains excessive background noise and weak analytical signals caused by near infrared overtones and combinations. That makes it difficult to achieve quantitative determinations of low concentration samples by NIR. A simple chemometric approach has been established to modify the noise frequency spectrum to improve NIR determinations. The proposed method is to multiply one Savitzky-Golay filtered NIR spectrum with another reference spectrum added with thermal noises before the other Savitzky-Golay filter. Since Savitzky-Golay filter is a kind of low-pass filter and cannot eliminate low frequency components of NIR spectrum, using one step or two consecutive Savitzky-Golay filter procedures cannot improve the determination of NIR greatly. Meanwhile, significant improvement is achieved via the Savitzky-Golay filtered NIR spectrum processed with the multiplication alteration before the other Savitzky-Golay filter. The frequency range of the modified noise spectrum shifts toward higher frequency regime via multiplication operation. So the second Savitzky-Golay filter is able to provide better filtering efficiency to obtain satisfied result. The improvement of NIR determination with tailoring noise frequency spectrum technique was demonstrated by both simulated dataset and two measured NIR spectral datasets. It is expected that noise frequency spectrum technique will be adopted mostly in applications where quantitative determination of low concentration sample is crucial.     

From UV to NIR: A Full-Spectrum Metal-Free Photocatalyst for Efficient Polymer Synthesis in Aqueous Conditions

Photo-mediation offers unparalleled spatiotemporal control over controlled radical polymerizations (CRP). Photo-induced electron/energy transfer reversible addition–fragmentation chain transfer (PET-RAFT) polymerization is particularly versatile owing to its oxygen tolerance and wide range of compatible photocatalysts. In recent years, broadband- and near-infrared (NIR)-mediated polymerizations have been of particular interest owing to their potential for solar-driven chemistry and biomedical applications. In this work, we present the first example of a novel photocatalyst for both full broadband- and NIR-mediated CRP in aqueous conditions. Well-defined polymers were synthesized in water under blue, green, red, and NIR light irradiation. Exploiting the oxygen tolerant and aqueous nature of our system, we also report PET-RAFT polymerization at the microliter scale in a mammalian cell culture medium.     

An emerging NIR super-long persistent phosphor and its applications

Materials with the ability to persistently emit intense near-infrared (NIR) light after ceasing excitation are very useful in many fields. The persistent time is a vital parameter for successful applications. In this study, we developed an emerging NIR super-long persistent luminescent (PersL) material, Cr³⁺-activated magnetoplumbite oxide La(Zn/Mg)(Ga,Al)₁₁O₁₉:Cr³⁺, by doping Yb³⁺ as a new efficient electron trap and incorporating Al³⁺ to engineer the energy band. We show that fine control of the trap depth and density is the key underpinning for PersL enhancement. The title material emits intense PersL in the spectral range of 600–950 nm with a PersL time of more than 1,000 h. Furthermore, after undergoing such long-term decay, the NIR emission can be revived by photo-/thermo-stimulation. We demonstrate its potential uses in bioimaging, multilevel anti-counterfeiting, tracing, and positioning. This study provides insight into how energy band engineering manipulates electronic structures to achieve high-performance PersL. The new NIR persistent phosphor may be soon utilized in related applications.     

A Novel NIR Fluorescent Probe for Highly Selective Detection of Nitroreductase and Hypoxic-Tumor-Cell Imaging

Nitroreductase as a potential biomarker for aggressive tumors has received extensive attention. In this work, a novel NIR fluorescent probe for nitroreductase detection was synthesized. The probe Py-SiRh-NTR displayed excellent sensitivity and selectivity. Most importantly, the confocal fluorescence imaging demonstrated that HepG-2 cells treated with Py-SiRh-NTR under hypoxic conditions showed obvious enhanced fluorescence, which means that the NTR was overexpressed under hypoxic conditions. Moreover, the probe showed great promise that could help us to study related anticancer mechanisms research.     

Anion‐Dependence of Ytterbium Complexes and Their NIR Luminescence

The reaction of 2‐aldehyde‐8‐hydroxyquinoline, histamine, and YbX₃ · 6H₂O (X = NO₃^–, ClO₄^–) affords two ytterbium complexes [Yb(nma)₂] · ClO₄ · 2CH₂Cl₂ ( 1 ) and [Yb(nma)(NO₃)₂(DMSO)] · CH₃OH ( 2 ) (Hnma = N‐(2‐(8‐hydroxylquinolinyl)methane(2‐(4‐imidazolyl)ethanamine))). The crystal structures were determined by X‐ray diffraction and it has been revealed that the anions have played important role in the assembly. In the case of 1 , the Yb³⁺ ions are completely encapsulated by two nma ligands with uncoordinated perchlorate anion balancing the positive charge. In the case of 2 , the Yb³⁺ ions are ligated by the ligand, oxygen atoms of the nitrate ion, and DMSO. Both complexes exhibit essential NIR luminescence of Yb³⁺ ions.     

The Ability of Near Infrared (NIR) Spectroscopy to Predict Functional Properties in Foods: Challenges and Opportunities

Near infrared (NIR) spectroscopy is considered one of the main routine analytical methods used by the food industry. This technique is utilised to determine proximate chemical compositions (e.g., protein, dry matter, fat and fibre) of a wide range of food ingredients and products. Novel algorithms and new instrumentation are allowing the development of new applications of NIR spectroscopy in the field of food science and technology. Specifically, several studies have reported the use of NIR spectroscopy to evaluate or measure functional properties in both food ingredients and products in addition to their chemical composition. This mini-review highlights and discussed the applications, challenges and opportunities that NIR spectroscopy offers to target the quantification and measurement of food functionality in dairy and cereals.     

Lanthanide-Based Probes for Imaging Detection of Enzyme Activities by NIR Luminescence,T1- and ParaCEST MRI

Applying a single molecular probe to monitor enzymatic activities in multiple, complementary imaging modalities is highly desirable to ascertain detection and to avoid the complexity associated with the use of agents of different chemical entities. We demonstrate here the versatility of lanthanide (Ln³⁺) complexes with respect to their optical and magnetic properties and their potential for enzymatic detection in NIR luminescence, CEST and T1 MR imaging, controlled by the nature of the Ln³⁺ ion, while using a unique chelator. Based on X-ray structural, photophysical, and solution NMR investigations of a family of Ln³⁺ DO3A-pyridine model complexes, we could rationalize the luminescence (Eu³⁺, Yb³⁺), CEST (Yb³⁺) and relaxation (Gd³⁺) properties and their variations between carbamate and amine derivatives. This allowed the design of $$ probes which undergo enzyme-mediated changes detectable in NIR luminescence, CEST and T1-weighted MRI, respectively governed by variations in their absorption energy, in their exchanging proton pool and in their size, thus relaxation efficacy. We demonstrate that these properties can be exploited for the visualization of β-galactosidase activity in phantom samples by different imaging modalities: NIR optical imaging, CEST and T1-weighted MRI.     

NIR and UV-vis spectroscopy, artificial nose and tongue: Comparison of four fingerprinting techniques for the characterisation of Italian red wines

Four rapid and low-cost vanguard analytical systems (NIR and UV-vis spectroscopy, a headspace-mass based artificial nose and a voltammetric artificial tongue), together with chemometric pattern recognition techniques, were applied and compared in addressing a food authentication problem: the distinction between wine samples from the same Italian oenological region, according to the grape variety.Specifically, 59 certified samples belonging to the Barbera d’Alba and Dolcetto d’Alba appellations and collected from the same vintage (2007) were analysed.The instrumental responses, after proper data pre-processing, were used as fingerprints of the characteristics of the samples: the results from principal component analysis and linear discriminant analysis were discussed, comparing the capability of the four analytical strategies in addressing the problem studied.     

A Kinetically Stabilized Nitrogen-Doped Triangulene Cation: Stable and NIR Fluorescent Diradical Cation with Triplet Ground State

A kinetically-stabilized nitrogen-doped triangulene cation derivative has been synthesized and isolated as the stable diradical with a triplet ground state that exhibits near-infrared emission. As was the case for a triangulene derivative we previously synthesized, the triplet ground state with a large singlet-triplet energy gap was experimentally confirmed by magnetic measurements. In contrast to the triangulene derivative, the nitrogen-doped triangulene cation derivative is highly stable even in solution under air and exhibits near-infrared absorption and emission because the alternancy symmetry of triangulene is broken by the nitrogen cation. Breaking the alternancy symmetry of triplet alternant hydrocarbon diradicals by a nitrogen cation would therefore be an effective strategy to create stable diradicals possessing magnetic properties similar to the parent hydrocarbons but with different electrochemical and photophysical properties.     

Application of NIR reflectance spectroscopy for the identification of pharmaceutical excipients

For manufacturing of medicaments, all ingredients must be reliably identified. Wet chemistry methods for identification of cellulose ethers, used by the Pharmacopoea Europea, is time consuming and expensive. To distinguish microcristalline and powdered cellulose, only unspecific sedimentation properties are used. However, applications as well as technological and pharmacokinetic properties of cellulose and various cellulose ethers are different.

NIR reflectance spectroscopy speeds up the identification of excipients. So this technique causes fewer delay in manufacturing processes. The discrimination of powdered and microcristalline celluloses as well as cellulose and cellulose ethers is made possible by factor analysis and soft independent modelling of class analogies (SIMCA). The classification was improved by spectral pretreatment multiplicative scatter correction (MSC), derivation and wavelength selection. The discrimination of powdered and microcristalline celluloses is statistically highly significant, so the identification can be done reliably. Cellulose ethers can be quickly identified by NIR spectroscopy, although a large number of samples of different manufacturers and physical properties, for example viscosity, were used. The only exception is the discrimination of methylcellulose and cellulose ethers containing methyl and hydroxyalkyl substituents, which show identical spectra. But even for those excipients, the wet chemistry expenses can be reduced to one test. The developed strategy for data evaluation is quite general in nature, hence it can be applied to other pharmaceutical powders, excipients and active components as well.