-
IUCrData Aug 2022In the V-shaped title Schiff base, CHNO, the planes of the benzene rings of the central di-phenyl-methane unit make a dihedral angle of 70.40 (5)°, whereas the planes...
In the V-shaped title Schiff base, CHNO, the planes of the benzene rings of the central di-phenyl-methane unit make a dihedral angle of 70.40 (5)°, whereas the planes of the neighbouring benzene and -vanilin rings are twisted with respect to one another by dihedral angles of 75.76 (5) and 73.89 (6)°. The Schiff base displays intra-molecular O-H⋯N hydrogen bonds and weak inter-molecular C-H⋯O contacts.
PubMed: 36340978
DOI: 10.1107/S2414314622007933 -
Cell Feb 2022ChRmine, a recently discovered pump-like cation-conducting channelrhodopsin, exhibits puzzling properties (large photocurrents, red-shifted spectrum, and extreme light...
ChRmine, a recently discovered pump-like cation-conducting channelrhodopsin, exhibits puzzling properties (large photocurrents, red-shifted spectrum, and extreme light sensitivity) that have created new opportunities in optogenetics. ChRmine and its homologs function as ion channels but, by primary sequence, more closely resemble ion pump rhodopsins; mechanisms for passive channel conduction in this family have remained mysterious. Here, we present the 2.0 Å resolution cryo-EM structure of ChRmine, revealing architectural features atypical for channelrhodopsins: trimeric assembly, a short transmembrane-helix 3, a twisting extracellular-loop 1, large vestibules within the monomer, and an opening at the trimer interface. We applied this structure to design three proteins (rsChRmine and hsChRmine, conferring further red-shifted and high-speed properties, respectively, and frChRmine, combining faster and more red-shifted performance) suitable for fundamental neuroscience opportunities. These results illuminate the conduction and gating of pump-like channelrhodopsins and point the way toward further structure-guided creation of channelrhodopsins for applications across biology.
Topics: Animals; Channelrhodopsins; Cryoelectron Microscopy; Female; HEK293 Cells; Humans; Ion Channel Gating; Male; Mice, Inbred C57BL; Models, Molecular; Optogenetics; Phylogeny; Rats, Sprague-Dawley; Schiff Bases; Sf9 Cells; Structure-Activity Relationship; Mice; Rats
PubMed: 35114111
DOI: 10.1016/j.cell.2022.01.007 -
IUCrData Feb 2020The title hemihydrate, CHN·0.5HO, was isolated from the condensation reaction of quinoline-2-carbaldehyde with 4-amino-4-1,2,4-triazole. The Schiff base mol-ecule...
The title hemihydrate, CHN·0.5HO, was isolated from the condensation reaction of quinoline-2-carbaldehyde with 4-amino-4-1,2,4-triazole. The Schiff base mol-ecule adopts an configuration about the C=N bond and is approximately planar, with a dihedral angle between the quinoline ring system and the 1,2,4-triazole ring of 12.2 (1)°. In the crystal, one water mol-ecule bridges two Schiff base mol-ecules O-H⋯N hydrogen bonds. The Schiff base mol-ecules are inter-connected by π-π stacking inter-actions [centroid-centroid distances of 3.7486 (7) and 3.9003 (7) Å] into columns along [10].
PubMed: 36340830
DOI: 10.1107/S2414314620001340 -
Molecules (Basel, Switzerland) Mar 2023Since the first reports of the reaction of imines and cyclic anhydrides by Castagnoli and Cushman, this procedure has been applied to the synthesis of a variety of... (Review)
Review
Since the first reports of the reaction of imines and cyclic anhydrides by Castagnoli and Cushman, this procedure has been applied to the synthesis of a variety of lactams, some of them with important synthetic or biological interest. The scope of the reaction has been extended to the use of various Schiff bases and anhydrides as well as to different types of precursors for these reagents. In recent years, important advances have been made in understanding the mechanism of the reaction, which has historically been quite controversial. This has helped to develop reaction conditions that lead to pure diastereomers and even homochiral products. In addition, these mechanistic studies have also led to the development of new multicomponent versions of the Castagnoli-Cushman reaction that allow products with more diverse and complex molecular structures to be easily obtained.
PubMed: 36985626
DOI: 10.3390/molecules28062654 -
IUCrData Jan 2020In the title hydrated Schiff base, CHNO·HO, the dihedral angle between the aromatic rings is 5.06 (11)° and an intra-molecular O-H⋯N hydrogen bond closes an S(6)...
In the title hydrated Schiff base, CHNO·HO, the dihedral angle between the aromatic rings is 5.06 (11)° and an intra-molecular O-H⋯N hydrogen bond closes an S(6) ring. In the crystal, O-H⋯O and O-H⋯N (w = water) hydrogen bonds link the components into centrosymmetric tetra-mers (two Schiff bases and two water mol-ecules). Longer N-H⋯O hydrogen bonds link the tetra-mers into [010] chains. A weak C-H⋯O hydrogen bond and aromatic π-π stacking between the pyrazine and phenyl rings [centroid-centroid separations = 3.604 (2) and 3.715 (2) Å] are also observed.
PubMed: 36337721
DOI: 10.1107/S2414314619017310 -
International Journal of Molecular... Jul 2023As stated by two of the seven papers [...].
As stated by two of the seven papers [...].
Topics: Coordination Complexes; Schiff Bases; Ligands
PubMed: 37446197
DOI: 10.3390/ijms241311014 -
ACS Omega Mar 2022Schiff bases represent an essential class in organic chemistry with antitumor, antiviral, antifungal, and antibacterial activities. The synthesis of Schiff bases...
Schiff bases represent an essential class in organic chemistry with antitumor, antiviral, antifungal, and antibacterial activities. The synthesis of Schiff bases requires the presence of an organic base as a catalyst such as piperidine. Base-free synthesis of organic compounds using a heterogeneous catalyst has recently attracted more interest due to the facile procedure, high yield, and reusability of the used catalyst. Herein, we present a comparative study to synthesize new Schiff bases containing indole moieties using piperidine as an organic base catalyst and Au@TiO as a heterogeneous catalyst. In both methods, the products were isolated in high yields and fully characterized using different spectral analysis techniques. The catalyst was reusable four times, and the activity was slightly decreased. The presence of Au increases the number of acidic sites of TiO, resulting in C=O polarization. Yields of the prepared Schiff bases in the presence of Au@TiO and piperidine were comparable. However, Au@TiO is an easily separable and recyclable catalyst, which would facilitate the synthesis of organic compounds without applying any hazardous materials. Furthermore, the luminescence behavior of the synthesized Schiff bases exhibited spectral shape dependence on the substituent group. Interestingly, the compounds also displayed deep-blue fluorescence with Commission Internationale de l'Éclairage (CIE) coordinates of < 0.1. Thus, these materials may contribute to decreasing the energy consumption of the emitting devices.
PubMed: 35382296
DOI: 10.1021/acsomega.1c06636 -
Molecules (Basel, Switzerland) Aug 2019Schiff base, an important family of reaction in click chemistry, has received significant attention in the formation of self-healing hydrogels in recent years. Schiff... (Review)
Review
Schiff base, an important family of reaction in click chemistry, has received significant attention in the formation of self-healing hydrogels in recent years. Schiff base reversibly reacts even in mild conditions, which allows hydrogels with self-healing ability to recover their structures and functions after damages. Moreover, pH-sensitivity of the Schiff base offers the hydrogels response to biologically relevant stimuli. Different types of Schiff base can provide the hydrogels with tunable mechanical properties and chemical stabilities. In this review, we summarized the design and preparation of hydrogels based on various types of Schiff base linkages, as well as the biomedical applications of hydrogels in drug delivery, tissue regeneration, wound healing, tissue adhesives, bioprinting, and biosensors.
Topics: Animals; Click Chemistry; Drug Delivery Systems; Humans; Hydrogels; Schiff Bases; Tissue Adhesives; Wound Healing
PubMed: 31430954
DOI: 10.3390/molecules24163005 -
IUCrData Mar 2024The title Si complex, CHNOSi, is built up by a tridentate dinegative Schiff base ligand bound to a sila-cyclo-hexane unit. The coordination geometry of the...
The title Si complex, CHNOSi, is built up by a tridentate dinegative Schiff base ligand bound to a sila-cyclo-hexane unit. The coordination geometry of the penta-coordinated Si atom is a distorted trigonal bipyramid. The presence of the sila-cyclo-hexane ring in the complex leads to an unusual coordination geometry of the Si atom with the N atom from the Schiff base ligand and an alkyl-C atom in apical positions of the trigonal bipyramid. There is a disorder of the methyl group at the imine bond with two orientations resolved for the H atoms [major orientation = 0.55 (3)]. In the crystal, C-H⋯O inter-actions are found within corrugated layers of mol-ecules parallel to the plane.
PubMed: 38586525
DOI: 10.1107/S2414314624002281 -
Molecules (Basel, Switzerland) Jan 2022Schiff bases are a vast group of compounds characterized by the presence of a double bond linking carbon and nitrogen atoms, the versatility of which is generated in the... (Review)
Review
Schiff bases are a vast group of compounds characterized by the presence of a double bond linking carbon and nitrogen atoms, the versatility of which is generated in the many ways to combine a variety of alkyl or aryl substituents. Compounds of this type are both found in nature and synthesized in the laboratory. For years, Schiff bases have been greatly inspiring to many chemists and biochemists. In this article, we attempt to present a new take on this group of compounds, underlining of the importance of various types of Schiff bases. Among the different types of compounds that can be classified as Schiff bases, we chose hydrazides, dihydrazides, hydrazones and mixed derivatives such as hydrazide-hydrazones. For these compounds, we presented the elements of their structure that allow them to be classified as Schiff bases. While hydrazones are typical examples of Schiff bases, including hydrazides among them may be surprising for some. In their case, this is possible due to the amide-iminol tautomerism. The carbon-nitrogen double bond present in the iminol tautomer is a typical element found in Schiff bases. In addition to the characteristics of the structure of these selected derivatives, and sometimes their classification, we presented selected literature items which, in our opinion, represent their importance in various fields well.
PubMed: 35164049
DOI: 10.3390/molecules27030787