Science and Arts,Philosophy and Science: Why after All? Why Not?

This perspective summarizes some interdisciplinary aspects of science and the relation to philosophy, also including the basic motivations and aims as they might be discussed with young scientists starting their careers and presented also in the form of a commencement speech. The contents of this speech were repeatedly discussed also with Jack Dunitz, who showed great interest in it, given his broad interests. The speech also referred to an earlier commencement speech by Jack Dunitz in 1989. In the introduction of our essay, we mention the early common history of science and humanities under the name of philosophy. This early history can be traced back to ancient Greek philosophy and the ‘academy’ of Platon in Athens with a history of more than 1000 years until closure in 529 AD, in modern times revived as the National Greek Academy in Athens in the 19th and 20th centuries. Other ‘academies’ in Europe started in the 17th century and had publications under various names involving ‘philosophy’ with a focus on what we call science (natural science) today. After about 1800 there was increasing fragmentation of the various fields of knowledge and philosophy was considered to be part of the modern ‘humanities’ quite separate from science, and the natural sciences were fragmented into physics, chemistry, biology etc., and even finer subdivisions. The essay also describes an effort at ETH Zurich, reintegrating the various subfields of science and also stressing an education of scientists and engineers in the humanities. The essay concludes with a discussion of several global risks for mankind and a scientific imperative to maintain life on Earth. The common aspects and the foundations of all sciences as fields of knowledge aiming for an understanding of the world around us and of human beings as part of it are discussed from various perspectives.     

Do enzymes sleep and work?

Single-enzyme studies suggest that dynamic disorder is a general characteristic of enzyme catalysis.     

Combining piracetam and lithium salts: ionic co-crystals and co-drugs?

Mechanochemical reaction of solid piracetam with the inorganic salts LiCl and LiBr yields ionic co-crystals which are also co-drugs, characterized by markedly different thermal properties with respect to pure components, also depending on the method for preparation and/or conditions of measurements; single crystal and powder X-ray diffraction at variable temperatures, DSC, TGA, hot stage microscopy (HSM) and intrinsic dissolution rate have been used to fully characterize the solid products.     

Epitopic Peptides Identified by LC?CELISA and LC?CMS

A new strategy of a liquid chromatography (LC)-enzyme linked immunosorbent assay (ELISA) combined with liquid chromatography-mass spectrometry (LC?CMS) was developed to identify the epitopic peptides for the antigen in Streptococcus suis. Metallendopeptidase, a potential antigen for S. suis, was digested by trypsin. The tryptic solution was separated by LC under optimal condition and collected into tubes. After it was dried using a cooling vacuum, the immunogenecity of peptides in each tube was investigated by ELISA against its corresponding antibody. All peptides in each tube with positive signals based on ELISA results were identified by LC?CMS. Accordingly, six putative peptides of metallendopeptidase were found and synthesized, all of which possessed high antigenicity recognized by the antibody.     

When and How Do Diaminocarbenes Dimerize?

No example of a simple uncatalyzed dimerization of a diaminocarbene has been clearly established, so it is timely to ask what factors control the thermodynamics of this reaction, and what mechanisms are responsible for the observed dimerizations? In agreement with qualitative experimental observations, the dimerizations of simple five‐ and six‐membered‐ring diaminocarbenes are calculated to be 100 kJ mol^?1 less favorable than those of acyclic counterparts. This large difference is semiquantitatively accounted for by bond and torsional angle changes around the carbene centers. Carbenes such as (Et₂N)₂C are kinetically stable in THF at 25 °C in agreement with calculated energy barriers, but they rapidly dimerize in the presence of the corresponding formamidinium ion. This proton‐catalyzed process is probably the most common mechanism for dimer formation, and involves formation of C‐protonated dimers, which can be observed in suitable cases. The possibility of alkali‐metal‐promoted dimerization is raised, and circumstantial evidence for this is presented.     

Preparation and properties of Al?B?Si composite pillared bentonite

Al–B–Si composite pillared clay was first prepared and its catalytic cracking properties for gas oil were investigated. Characterization techniques included XRD, BET and IR spectroscopy of pyridine adsorbed. It is shown by the results that the introduction of Si enhanced the catalytic activity and gasoline yield on pillared clay. Al–B–Si composite pillared clay was a better catalyst material.

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Al–B–Si . , . , Si . Al–B–Si .

     

Synthesis and Crystal Structure Analysis of 5?-O-Tosyl-2,3?-anhydrothymidine

In this paper, 5?-O-tosyl-2,3?-anhydrothymidine has been synthesized and its crystal structure was analyzed. The crystal belongs to the triclinic system, space group P1, with a = 5.397(2), b = 6.1886(18), c = 3.507(5) ?, α ?= 87.74(2), β ?= 89.84(4), γ ?= 73.79(2)°, C17H18N2O6S, Mr = 378.39, Z = 1, V = 432.8(3) ?3, Dc = 1.452 g/cm3, F(000) = 198 and Flack = -0.11(14). No intermolecular hydrogen bonds exist in the crystal, and the angle between benzene ring and pyrimidine planes is 32.23°.     

Are isatin and isatoic anhydride antiaromatic and aromatic respectively? A combined experimental and theoretical investigation

This paper reports the results of our thermochemical/calorimetric determination of the enthalpies of combustion, phase change, and formation of isatin, isatoic anhydride, and N-methylisatin. The density functional calculations accompanied by vibrational and thermal corrections were also performed for these compounds and N-methylisatoic anhydride. Through a combination of theoretical calculations and associated isodesmic reactions, we have deduced that isatin has some antiaromatic character and isatoic anhydride enjoys some aromatic stabilization.     

Can proteins and crystals self-catalyze methyl rotations?

The chi (C(alpha)-C(beta)) torsional barrier in the dipeptide alanine (N-methyl-l-alanyl-N-methylamide) crystal was investigated using ab initio calculations at various levels of theory, molecular mechanics, and molecular dynamics. For one of the two molecules in the asymmetric unit the calculations suggest that rotation around the chi dihedral angle is catalyzed by the crystal environment, reducing by up to approximately 2kT the torsional barrier in the crystal with respect to that in the gas phase. This catalytic effect is present at both low and room temperature and originates from a van der Waals destabilization of the minima in the methyl dihedral potential coming from the nonbonded environment of the side chain. Screening of a subset of the Protein Data Bank with a pharmacophore model reproducing the crystal environment around this side chain methyl identified a protein containing an alanine residue with an environment similar to that in the crystal. Calculations indicate that this chi torsional barrier is also reduced in the protein at low temperature but not at room temperature. This suggests that environment-catalyzed rotation of methyl groups can occur both in the solid phase and in native biological structures, though this effect might be temperature-dependent. The relevance of this catalytic effect is discussed in terms of its natural occurrence and its possible contribution to the low-frequency vibrational modes of molecules.     

Are axial and radial flow chromatography different?

Radial flow chromatography can be a solution for scaling up a packed bed chromatographic process to larger processing volumes. In this study we compared axial and radial flow affinity chromatography both experimentally and theoretically. We used an axial flow column and a miniaturized radial flow column with a ratio of 1.8 between outer and inner surface area, both with a bed height of 5 cm. The columns were packed with affinity resin to adsorb BSA. The average velocity in the columns was set equal. No difference in performance between the two columns could be observed. To gain more insight into the design of a radial flow column, the velocity profile and resin distribution in the radial flow column were calculated. Using mathematical models we found that the breakthrough performance of radial flow chromatography is very similar to axial flow when the ratio between outer and inner radius of the radial flow column is around 2. When this ratio is increased, differences become more apparent, but remain small. However, the ratio does have a significant influence on the velocity profile inside the resin bed, which directly influences the pressure drop and potentially resin compression, especially at higher values for this ratio. The choice between axial and radial flow will be based on cost price, footprint and packing characteristics. For small-scale processes, axial flow chromatography is probably the best choice, for resin volumes of at least several tens of litres, radial flow chromatography may be preferable.     

Anharmonic C?H and C=O Interactions in Peptide and Sugar

C?H and C=O stretching modes are two among many structural and dynamic probes of proteins and peptides in condensed phases. Anharmonic properties of these two modes in peptide and sugar have been examined using a second-order perturbative vibrational approach. High order force constants were obtained and examined to ˉnd how crucial they are in determining the degree of mode localization and the nature of mode anharmonicity of the two stretching modes. It is found that the C?H mode is highly localized,and its diagonal anharmonicity is mainly determined by the mode itself. However, the C=O mode is largely delocalized, and the diagonal anharmonicity involves contributions from other modes. The o?-diagonal anharmonicity between C?D and C=O modes is found to be negative in deuterated species, di?ering from those of the non-deuterated ones. It is also found that inter-mode interaction between each of the two modes with low-frequency modes contribute signiˉcantly to the o?-diagonal anharmonicity. These low-frequency modes give rise to a network of energy relaxation or intramolecular vibrational energy redistribution pathways which can be used to examine temporal behavior of intramolecular vibration energy °ow, provided a femtosecond broadband two-dimensional infrared spectroscopy is available.     

Zethrene and Dibenzozethrene: Masked Biradical Molecules?

The syntheses, structures, and physical properties of dibenzozethrenes were explored. The results thus obtained were compared with those for zethrenes. Dibenzozethrenes were synthesized by the nickel‐catalyzed cyclodimerization of 9‐ethynyl‐1‐iodoanthracenes. The substituents in zethrene and dibenzozethrene twisted their backbones, and remarkably influenced their properties. Unlike closed‐shell disubstituted derivatives, the parent zethrene and dibenzozethrene are singlet open‐shell biradicals, which were studied by variable‐temperature ¹H NMR, ESR, SQUID and computational methods. Since substituents were observed to affect significantly the biradical properties, the relevant mechanisms were analyzed. The nonlinear optical performance of each of these compounds depends on its π‐conjugation and biradical properties. Dibenzozethrenes have larger two‐photon absorption cross‐sections than zethrenes, as most strongly evidenced by the parent dibenzothrene [σ_max=4323 GM at 530 nm].     

Are analytical standards and reagents really reliable?

Quality assurance is one of the major challenges in analytical chemistry, whatever the scope of application. The quality of analytical standards is very seldom questioned; however, sometimes odd results are obtained, and all the other potential sources of discrepancies are eliminated. So, we investigated the reliability of three analytical standards and reagents implemented for radiochemical and chemical characterizations of nuclear waste. In particular, this work examined the purity of a source of tritiated dodecane, the trueness of a certified concentration value and the purity for a diethylenetriaminepentaacetic acid (DTPA) reagent and the trueness of a certified concentration value for a multi-anion standard used in an interlaboratory comparison exercise. It was shown that the source of tritiated dodecane contains 60 % of tritiated impurities. The trueness of the DTPA concentration certified by the supplier was questioned due to the presence of impurities in the solution. It was proven that the long-term stability of the multi-anion standard was not guaranteed for nitrite. The results clearly demonstrated that, despite the certificates delivered by the suppliers, caution has to be taken toward the reliability of the analytical standards and reagents.     

Oxygen and Osmium-A New Alliance for Dihydroxylations?

The activation of oxygen in new synthetic procedures dramatically expands the scope of osmium-catalyzed dihydroxylations [Eq. (1)]. Even air can now be used as the cooxidant in the asymmetric version of this reaction with little loss of selectivity.     

Zethrene and Dibenzozethrene: Masked Biradical Molecules?

The syntheses, structures, and physical properties of dibenzozethrenes were explored. The results thus obtained were compared with those for zethrenes. Dibenzozethrenes were synthesized by the nickel‐catalyzed cyclodimerization of 9‐ethynyl‐1‐iodoanthracenes. The substituents in zethrene and dibenzozethrene twisted their backbones, and remarkably influenced their properties. Unlike closed‐shell disubstituted derivatives, the parent zethrene and dibenzozethrene are singlet open‐shell biradicals, which were studied by variable‐temperature ¹H NMR, ESR, SQUID and computational methods. Since substituents were observed to affect significantly the biradical properties, the relevant mechanisms were analyzed. The nonlinear optical performance of each of these compounds depends on its π‐conjugation and biradical properties. Dibenzozethrenes have larger two‐photon absorption cross‐sections than zethrenes, as most strongly evidenced by the parent dibenzothrene [σ_max=4323 GM at 530 nm].     

C-H?Br, C-Br?Br, and C-Br?π interactions in the crystal structures of mesitylene- and dimesitylmethane-derived compounds bearing bromomethyl units

X-ray structure determinations of mesitylene- and dimesitylmethane-derived compounds bearing bromomethyl units (compounds 1-3) show that the crystal packing of the molecules is characterized by the presence of C-H?Br interactions, such as BrCH₂?Br, CH₃?Br, and C_PhH?Br. In addition, C-Br?Br and C-Br?π interactions determine the crystal packing. The bromomethyl groups play a major role in the packing of 1-3.     

2D and 3D supramolecular assemblies of double cyclopalladated azobenzenes realized by C-H?Cl-Pd, π?π and C-H?π interactions

The double cyclopalladated complex with azobenzene, μ-[(E)-1,2-diphenyldiazene-C^2,8, N^1,2]-di-[chloro(dimethylsulfoxide)palladium(II)]; (DMSO)PdCl(μ-C₆H₄NNC₆H₄)(DMSO)PdCl (1) and its analogous complex with DMF as ancillary ligand, (DMF)PdCl(μ-C₆H₄NNC₆H₄)(DMF)PdCl; μ-[(E)-1,2-diphenyldiazene-C^2,8,N^1,2]-di-[chloro(dimethylformamide)palladium(II)] (2a) were synthesized and the function of cyclopalladated moiety in molecular assembling in the solid state is illustrated by their crystal packings. The polymorphism of 2a and 2b is discussed. The crystal structures reveal assemblies with molecular components self-organized by C-H?Cl-Pd hydrogen bonds, π?π, and C-H?π interactions. The double cyclopalladated complexes of azobenzene, with two Pd-Cl moieties participating in the hydrogen bond formation and π-conjugated system involved in the π?π or C-H?π interactions, represent a new class of building blocks for construction of solid state supramolecular assemblies.     

Death,taxes, and the genetic code?

The genetic code is an enduring feature of biology: only rare circumstances result in changes to translation of the code, at least in nature. Researchers are devising methods to engineer ribosome-synthesized polypeptides containing novel and potentially useful amino acids.     

Preparation and characterization of Ru?Pb supported catalysts

Decomposition of Mn₃Mo₂TeO₁₂ during oxidation of toluene to benzaldehyde was observed. Depending on the surface composition of the initial catalyst, the decomposition leads to less active but highly selective MnMoTeO₆ or to MnMoO₄ which is not selective in toluene oxidation.

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Mn₃Mo₂TeO₁₂ . , MnMoTeO₆, MnMoO₆.