Isomer-Specific Induced Circular Dichroism Spectroscopy of Jet-Cooled Phenol Complexes with (-)-Methyl l-Lactate

Induced circular dichroism (ICD) is the CD observed in the absorption of an achiral molecule bound to a transparent chiral molecule through noncovalent interactions. ICD spectroscopy has been used to probe the binding between molecules, such as protein-ligand interactions. However, most ICD spectra have been measured in solution, which only exhibit the averaged CD values of all conformational isomers in solution. Here, we obtained the first isomer-selective ICD spectra by applying resonant two-photon ionization CD spectroscopy to jet-cooled phenol complexes with (-)-methyl l-lactate (PhOH-(-)ML). The well-resolved CD bands in the spectra were assigned to two conformers, which contained different types of hydrogen-bonding interactions between PhOH and (-)ML. The ICD values of the two conformers have different signs and magnitudes, which were explained by differences both in the geometrical asymmetries of PhOH bound to (-)ML and in the electronic coupling strengths between PhOH and (-)ML.

Origin of Both Right- and Left-Handed Helicities in a Supramolecular Gel with and without Ni2+ at the Supramolecular Level

We demonstrate the different origins of helical directions in polymeric gels derived from a hydrazone reaction in the absence and presence of Ni²⁺. The right-handed helicity of polymeric gels without Ni²⁺ originates from the enantiomeric d-form alanine moiety embedded in the building block. However, the right-handed helicity is inverted to a left-handed helicity upon the addition of Ni²⁺, indicating that added Ni²⁺ greatly affects the conformation of the polymeric gel by overcoming the influence of the enantiomer embedded in the building block on the helicity at the supramolecular level. More interestingly, the ratio of the right-toleft-handed helical fibers varies with the concentration of Ni²⁺, which converts from 100% right-handed helical fiber to 90% left-handed helical fiber. In the presence of Ni²⁺, both right- and left-handed helical fibers coexist at the supramolecular level. Some fibers also exhibit both right- and left-handed helicities in a single fiber.

Crystal structure of N-[2-(cyclo-hexyl-sulfan-yl)eth-yl]quinolinic acid imide

The title compound, C15H18N2O2S {systematic name: 6-[2-(cyclo-hexyl-sulfan-yl)eth-yl]-5H-pyrrolo-[3,4-b]pyridine-5,7(6H)-dione}, was obtained from the reaction of pyridine-2,3-di-carb-oxy-lic anhydride (synonym: quinolinic anhydride) with 2-(cyclo-hexyl-sulfan-yl)ethyl-amine. The dihedral angle between the mean plane of the cyclo-hexyl ring and the quinolinic acid imide ring is 25.43 (11)°. In the crystal, each mol-ecule forms two C-H⋯O hydrogen bonds and one weak C-O⋯π [O⋯ring centroid = 3.255 (2) Å] inter-action with neighbouring mol-ecules to generate a ladder structure along the b-axis direction. The ladders are linked by weak C-O⋯π [O⋯ring centroid = 3.330 (2) Å] inter-actions, resulting in sheets extending parallel to the ab plane. The mol-ecular structure is broadly consistent with theoretical calculations performed by density functional theory (DFT).

Crystal structure of N,N'-di-decyl-pyromellitic di-imide

The title compound, C30H44N2O4 [systematic name: 2,6-di-decyl-pyrrolo-[3,4-f]iso-indole-1,3,5,7(2H,6H)-tetra-one], consists of a central pyromellitic di-imide moiety with terminal decyl groups at the N-atom positions. The centre of the mol-ecule lies on a crystallographic inversion centre so the asymmetric unit contains one half-mol-ecule. The mol-ecule exhibits a rod-shaped conformation, like other similar compounds of this type, the distance between the ends of terminal decyl groups being 32.45 Å. The packing is dominated by a lamellar arrangement of the mol-ecules, which is reinforced by C-H⋯O hydrogen bonds and C-O⋯π inter-actions, forming a classic herringbone structure. The mol-ecular structure is consistent with the theoretical calculations performed by density functional theory (DFT).

Preventing the development of SLE: identifying risk factors and proposing pathways for clinical care

Although challenging, developing evidence-based approaches to an early and accurate diagnosis of systemic lupus erythematosus is a key approach to preventing disease and lupus-associated morbidity and mortality. Advances in our understanding of preclinical and incomplete lupus erythematosus have enabled the identification of risk factors that may predict disease and the development of potential strategies aimed at primary prevention. Emerging data support the notion that there is a temporal disease progression from initial asymptomatic autoimmunity (preclinical lupus) through early clinical features of the disease (incomplete lupus erythematosus) to finally becoming fully classifiable systemic lupus erythematosus (complete lupus erythematosus). Here, we review the demographic, clinical, biomarker as well as genetic and environmental features that are reported to increase the risk of disease progression. Based on these risk factors, we propose a clinical care pathway for patients with early disease. We envisage that such a pathway, through early identification of disease, may improve patient outcomes, while reducing health care costs.

Conformational structures of jet-cooled acetaminophen-water clusters: a gas phase spectroscopic and computational study

Jet-cooled acetaminophen (AAP)-water clusters, AAP-(H₂O)₁, were investigated by mass-selected resonant two-photon ionization (R2PI), ultraviolet-ultraviolet hole-burning (UV-UV HB), infrared-dip (IR-dip), and infrared-ultraviolet hole-burning (IR-UV HB) spectroscopy. Each syn- and anti-AAP rotamer has three distinctive binding sites (-OH, >CO, and >NH) for a water molecule, thus 6 different AAP-(H₂O)₁ conformers are expected to exist in the molecular beam. The origin bands of the AAP(OH)-(H₂O)₁ and AAP(CO)-(H₂O)₁ conformers (including their syn- and anti-conformers) in the R2PI spectrum are shifted to red and blue compared to those of the AAP monomer, respectively. These frequency shifts upon complexation between a water molecule and a specific binding site of AAP are also predicted by theoretical calculations. The spectral assignments of the origin bands in the R2PI spectra and the IR vibrational bands in the IR-dip spectra of the four lowest-energy conformers of AAP-(H₂O)₁, [syn- and anti-AAP(OH)-(H₂O)₁ and syn- and anti-AAP(CO)-(H₂O)₁], are aided by ab initio and time-dependent density functional theory (TDDFT) calculations. Further investigation of the IR-dip spectra has revealed a hydrogen-bonded NH stretching mode, supporting the presence of the syn-AAP(NH)-(H₂O)₁ conformer. Moreover, by employing IR-UV HB spectroscopy, we have reconfirmed the existence of the syn-AAP(NH)-(H₂O)₁ conformer, which happened to be buried underneath the broad background contributed by the AAP(OH)-(H₂O)₁ conformers. These observations have led us to conclude that all of the possible conformers of AAP-(H₂O)₁ have been found in this study.

Self-Assembled Tb3+ Complex Probe for Quantitative Analysis of ATP during Its Enzymatic Hydrolysis via Time-Resolved Luminescence in Vitro and in Vivo

To more accurately assess the pathways of biological systems, a probe is needed that may respond selectively to adenosine triphosphate (ATP) for both in vitro and in vivo detection modes. We have developed a luminescence probe that can provide real-time information on the extent of ATP, ADP, and AMP by virtue of the luminescence and luminescence lifetime observed from a supramolecular polymer based on a C₃ symmetrical terpyridine complex with Tb³⁺ (S1-Tb). The probe shows remarkable selective luminescence enhancement in the presence of ATP compared to other phosphate-displaying nucleotides including adenosine diphosphate (ADP), adenosine monophosphate (AMP), guanosine triphosphate (GTP), thymidine triphosphate (TTP), H₂PO₄^- (Pi), and pyrophosphate (PPi). In addition, the time-resolved luminescence lifetime and luminescence spectrum of S1-Tb could facilitate the quantitative measurement of the exact amount of ATP and similarly ADP and AMP within living cells. The time-resolved luminescence lifetime of S1-Tb could also be used to quantitatively monitor the amount of ATP, ADP, and AMP in vitro following the enzymatic hydrolysis of ATP. The long luminescence lifetime, which was observed into the millisecond range, makes this S1-Tb-based probe particularly attractive for monitoring biological ATP levels in vivo, because any short lifetime background fluorescence arising from the complex molecular environment may be easily eliminated.

Photodissociation kinetics of the isobutanal radical cation: a combined experimental and theoretical study

Main photodissociation pathways of isobutanal radical cation generated by (2 + 1) REMPI process.

Cirmtuzumab inhibits Wnt5a-induced Rac1 activation in chronic lymphocytic leukemia treated with ibrutinib

Signaling via the B cell receptor (BCR) plays an important role in the pathogenesis and progression of chronic lymphocytic leukemia (CLL). This is underscored by the clinical effectiveness of ibrutinib, an inhibitor of Bruton's tyrosine kinase (BTK) that can block BCR-signaling. However, ibrutinib cannot induce complete responses (CR) or durable remissions without continued therapy, suggesting alternative pathways also contribute to CLL growth/survival that are independent of BCR-signaling. ROR1 is a receptor for Wnt5a, which can promote activation of Rac1 to enhance CLL-cell proliferation and survival. In this study, we found that CLL cells of patients treated with ibrutinib had activated Rac1. Moreover, Wnt5a could induce Rac1 activation and enhance proliferation of CLL cells treated with ibrutinib at concentrations that were effective in completely inhibiting BTK and BCR-signaling. Wnt5a-induced Rac1 activation could be blocked by cirmtuzumab (UC-961), an anti-ROR1 mAb. We found that treatment with cirmtuzumab and ibrutinib was significantly more effective than treatment with either agent alone in clearing leukemia cells in vivo. This study indicates that cirmtuzumab may enhance the activity of ibrutinib in the treatment of patients with CLL or other ROR1⁺ B-cell malignancies.

Crystal structure of fluroxypyr

In the title pyridine herbicide {systematic name: 2-[(4-amino-3,5-di-chloro-6-fluoro-pyridin-2-yl)-oxy]acetic acid}, C7H5Cl2FN2O3, the mean plane of the carb-oxy-lic acid substituent and the pyridyl ring plane subtend a dihedral angle of 77.5 (1)°. In the crystal, pairs of O-H⋯O hydrogen bonds form inversion dimers with R22(8) ring motifs. These are extended into chains along [011] by N-H⋯F hydrogen bonds. In addition, inter-molecular N-H⋯O hydrogen bonds and weak π-π inter-actions [ring centroid separation = 3.4602 (9) Å] connect these chains into a three-dimensional network.

Enhanced dechlorination of m-DCB using iron@graphite/palladium (Fe@C/Pd) nanoparticles produced by pulsed laser ablation in liquid

In this work, the zero valent Fe (ZVI) and graphite-encapsulated Fe (Fe@C) nanoparticles (NPs) were easily and selectively prepared by a pulsed laser ablation (PLA) method in an aqueous sodium borohydride solution and ascorbic acid dissolved in methanol, respectively. Here, the Fe@C NPs were uniquely synthesized by PLA in methanol, where the solvent is used as both a carbon source for the graphitic layers and solvent, which is very unique. Furthermore, Pd NPs were loaded onto the surface of the Fe@C NPs to prepare bimetallic (Fe@C/Pd) NPs for the enhancement of the degradation efficiency of m-dichlorobenzene (m-DCB). The morphology, crystallinity, and surface composition of the prepared NPs were carefully characterized by high-resolution transmission electron microscopy (HRTEM), energy dispersive x-ray spectrometer (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The degradation rate of m-DCB using single (Fe and Pd) or bimetallic (Fe/Pd and Fe@C/Pd) NPs were compared by using gas chromatography. Among these NPs produced in this work, the Fe@C/Pd NPs with 1.71 wt % of Pd showed an excellent dechlorination efficiency for m-DCB with 100% degradation within 75 min. The graphitic layer on the Fe NPs played as not only an oxidation resistant for the Fe NPs to surroundings, but also a supporter of the Pd NPs for the enhanced degradation efficiency of m-DCB.

Determining Chiral Configuration of Diamines via Contact Angle Measurements on Enantioselective Alanine-Appended Benzene-Tricarboxamide Gelators

Spectroscopic techniques exist that may discern between enantiomers and assess chiral purity. A nonspectroscopic approach that may be directly observed could provide numerous benefits. Using chiral alanine-appended benzene-tricarboxamide gelators, we reveal a methanol gel system that is capable of providing visual discrimination between enantiomers of various diamines. Specifically, gelation is induced by supramolecular nanofiber assembly resulting from interaction between a chiral gelator and a diamine of opposing chirality (i.e., a heterochiral system). Upon further implementing the chiral gelator in electrospun fibers as solid state films, we revealed enantioselective surface wetting properties that allowed for determining chirality through contact angle measurements. While these two approaches of observable gelation and surface wetting offer nonspectroscopic approaches, we also find that the supramolecular nanofiber assembly was able to enhance the induced circular dichroism signal resulting from addition of chiral diamines, allowing precise quantification of their enantiomeric purity.

How complexity emerges in urban systems: Theory of urban morphology

Human beings develop the land and transform land use patterns, constructing artificial structures. Among them, the city is a representative system and its morphology has attracted much attention. While most existing studies have been devoted to individual dynamics and focused on the proximity of specific areas of a city, we here pay attention to the city as a complex system, where interactions between individuals give rise to emergent properties. Specifically, analyzing the big data on every building in Seoul City, we specify the relevant interactions among constituents and probe the emergence of complex land use patterns. In particular, based on the empirical observations, we illustrate that interactions between land uses are frustrated, which serves as a basic postulate of the theory of urban morphology. We examine this conjecture with the help of a layered Ising-type model and disclose that the actual land use pattern emerges at the criticality of the system in the presence of heterogeneously distributed fields. It is also remarked that our model, allowing quantitative predictions, can easily be applied to other cities around the world.

Fluorescence imaging for Fe3+ in Arabidopsis by using simple naphthalene-based ligands

Naphthalene-based probes 1 and 1A were found to dramatically decrease fluorescence upon addition of Fe³⁺, but not with other metal ions. Furthermore, 1 and 1A displayed high fluorescence quenched-imaging for Fe³⁺ in Arabidopsis as well as nanofibruous films.

NMR detection of chirality and enantiopurity of amines by using benzene tricarboxamide-based hydrogelators as chiral solvating agents

The use of gelator 1D as a means for NMR-based determination of the enantiopurity and chirality of amines.