[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

4. Survey of Novel Multiphoton Active Materials 1257 4.1. Multiphoton Absorbing Systems 1257 4.2. Organic Molecules 1257 4.3. Organic Liquids and Liquid Crystals 1259 4.4. Conjugated Polymers 1259 4.4.1. Polydiacetylenes 1261 4.4.2. Polyphenylenevinylenes (PPVs) 1261 4.4.3. Polythiophenes 1263 4.4.4. Other Conjugated Polymers 1265 4.4.5. Dendrimers 1265 4.4.6. Hyperbranched Polymers 1267 4.5. Fullerenes 1267 4.6. Coordination and Organometallic Compounds 1271 4.6.1. Metal Dithiolenes 1271 4.6.2. Pyridine-Based Multidentate Ligands 1272 4.6.3. Other Transition-Metal Complexes 1273 4.6.4. Lanthanide Complexes 1275 4.6.5. Ferrocene Derivatives 1275 4.6.6. Alkynylruthenium Complexes 1279 4.6.7. Platinum Acetylides 1279 4.7. Porphyrins and Metallophophyrins 1279 4.8. Nanoparticles 1281 4.9. Biomolecules and Derivatives 1282 5. Nonlinear Optical Characterizations of Multiphoton Active Materials 1282

Multiphoton Absorbing Materials : Molecular Designs, Characterizations, and Applications

Bioconjugation methodologies have proven to play a central enabling role in the recent development of biotherapeutics and chemical biology approaches. Recent endeavours in these fields shed light on unprecedented chemical challenges to attain bioselectivity, biocompatibility, and biostability required by modern applications. In this review the current developments in various techniques of selective bond forming reactions of proteins and peptides were highlighted. The utility of each endogenous amino acid-selective conjugation methodology in the fields of biology and protein science has been surveyed with emphasis on the most relevant among reported transformations; selectivity and practical use have been discussed.

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Developments and recent advancements in the field of endogenous amino acid selective bond forming reactions for bioconjugation

Update 1 of: Electrophilicity Index

Two-dimensional (2D) materials with planar hypercoordinate motifs are extremely rare due to the difficulty in stabilizing the planar hypercoordinate configurations in extended systems. Furthermore, such exotic motifs are often unstable. We predict a novel Cu2Si 2D monolayer featuring planar hexacoordinate copper and planar hexacoordinate silicon. This is a global minimum in 2D space which displays reduced dimensionality and rule-breaking chemical bonding. This system has been studied with density functional theory, including molecular dynamics simulations and electronic structure calculations. Bond order analysis and partitioning reveals 4c–2e σ bonds that stabilize the two-dimensional structure. We find that the system is quite stable during short annealing simulations up to 900 K, and predict that it is a nonmagnetic metal. This work opens up a new branch of hypercoordinate two-dimensional materials for study.

Two-dimensional Cu2Si monolayer with planar hexacoordinate copper and silicon bonding.

We summarize our contributions on the quest of new planar tetracoordinate carbon entities (new carbon molecules with exotic chemical structures and strange bonding schemes). We give special emphasis on the rationalization why in this type of molecules the planar configuration is favored over the tetrahedral one. We will concentrate on the latter and will show that molecules containing planar tetracoordinate carbons have a stabilizing system of delocalized pi electrons, which shows similar properties as pi systems in aromatic molecules.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/jcc.20515

Recent advances in planar tetracoordinate carbon chemistry

A series of molecules, based on the smallest carbon cluster with one planar tetracoordinate carbon atom, C52-, are presented. To gain a better understanding about which electronic factors contribute to their stabilization, several global reactivity indexes, molecular scalar fields, and magnetic responses were calculated. The optimized bond lengths and the topological analysis of the electron density show that the central carbon atom in the parent dianion C52- has a planar local environment, and it is coordinated to four other carbon atoms. The bonding of the parent dianion with the metal cations is highly ionic. The magnetic properties show that the C52- derivatives are strongly diatropic and have a remarkable transferability of structural and electronic features from the anion to the salts. The theoretical analysis suggests that the lithium salt, C5Li2, is the most plausible candidate for experimental detection.

Theoretical Analysis of the Smallest Carbon Cluster Containing a Planar Tetracoordinate Carbon

A recently proposed system with a central planar tetracoordinate carbon linking two three-membered rings, C52-, lends itself to extension in one, two, and three dimensions. Our construction of potential realizations begins with an analysis of the electronic structure of C52-. Dimers such as C10Li3-, C10Li4, and a trimer C15Li6 are then examined, and their geometries are optimized to find clues for ways the C52- unit may polymerize in the presence of countercations. Coordination through the terminal carbons is favored in the oligomers and polymers; several electronically and structurally reasonable systems of the stoichiometry C5Mx (M = Li, x = 2; M = Be, Pt, Zn, x = 1) emerge from band structure calculations and energetic considerations.

Planar tetracoordinate carbon in extended systems.

By highly correlated ab initio methods and DFT calculations, we have shown that alkaline metals can stabilize planar tetracoordinate carbon-containing molecules with the C(C4) skeleton. This family of molecules is C5M2, where M is an alkaline metal. The stability of these compounds is rationalized in terms of the delocalization of the p-orbital perpendicular to the molecular plane, the global hardness, and the electrophilicity. The analysis of several molecular scalar fields shows that the bonding between the C52- dianion and the metals is strongly ionic. The structures reported are the first examples with a planar tetracoordinate carbon, surrounded by carbon atoms, and stabilized, only, by electronic factors.

(C5M2-n)n- (M = Li, Na, K, and n = 0, 1, 2). A New Family of Molecules Containing Planar Tetracoordinate Carbons

Yogurt is a highly consumed dairy product, regarded as healthy. The objective of this study was to fortify a set-type yogurt with two levels of iron oxide, zinc oxide, and calcium phosphate nanoparticles. Minerals were also used to make a comparison between nano and micro-sized minerals, to determine their effect on the physicochemical and rheological properties during 28 days of storage. The pH decreased while acidity increased in all samples during storage. Density and moisture did not show differences between samples, or during storage. Color parameters showed variations in iron-fortified samples, whereas an increase in net color change through storage was recorded for all samples. Syneresis increased significantly in micro-mineral samples, being lower in nano-fortified ones; during storage the separation significantly increased in all samples. The Herschel-Bulkley flow model fitted well the non-Newtonian behavior of the yogurt. The yogurts fortified with calcium and zinc nanoparticles increased their consistency and firmness concerning to the other samples, both parameters decreased during storage in all samples; yield stress and flow index did not significantly change during storage. In vitro digestion analysis of the yogurt with nanoparticles showed more solubility than micro-minerals, for the three minerals. In general, nanoparticles showed advantages over conventional fortification.

Miguel A. Méndez-Rojas

Papers

Recent advances in planar tetracoordinate carbon chemistry

Theoretical Analysis of the Smallest Carbon Cluster Containing a Planar Tetracoordinate Carbon

Planar tetracoordinate carbon in extended systems.

(C5M2-n)n- (M = Li, Na, K, and n = 0, 1, 2). A New Family of Molecules Containing Planar Tetracoordinate Carbons

Fortification of yogurt with nano and micro sized calcium, iron and zinc, effect on the physicochemical and rheological properties