Five Membered Rings
Five Membered Rings - Related Videos
01:13
Five-Membered Heterocyclic Aromatic Compounds: Overview
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2023
Heterocyclic aromatic compounds are cyclic compounds that are aromatic and have one or more heteroatoms—atoms other than carbon, in the ring. Depending upon the number of atoms present in the ring, they can be either five or six-membered. Examples of five-membered heterocyclic aromatic compounds include pyrrole, furan, thiophene, and imidazole. Pyrrole consists of one nitrogen atom having one lone pair of electrons. Furan and thiophene have one oxygen and one sulfur heteroatom, respectively.
08:00
Directed Cellular Self-Assembly to Fabricate Cell-Derived Tissue Rings for Biomechanical Analysis and Tissue Engineering
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Cited by 39 •
2011
This article outlines a versatile method to create cell-derived tissue rings by cellular self-assembly. Smooth muscle cells seeded into ring-shaped agarose wells aggregate and contract to form robust three-dimensional (3D) tissues within 7 days. Millimeter-scale tissue rings are conducive to mechanical testing and serve as building blocks for tissue assembly.
09:20
The Assembly and Application of 'Shear Rings': A Novel Endothelial Model for Orbital, Unidirectional and Periodic Fluid Flow and Shear Stress
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Cited by 10 •
2016
Different levels and patterns of fluid shear are known to modulate endothelial gene expression, phenotype and susceptibility to disease. We discuss the assembly and use of 'shear rings': a model that produces unidirectional, periodic shear stress patterns. Shear rings are simple to assemble, economical and can produce high cell yields.
08:30
X-ray Dose Reduction through Adaptive Exposure in Fluoroscopic Imaging
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Cited by 2 •
2011
We are developing a dynamic adaptive exposure technique using our scanning beam digital X-ray system. Rather than exposing an object uniformly, the exposure is adapted depending on the opacity of the object. Here we show an experiment on an anthropomorphic phantom that resulted in a dose saving of 30%.
09:51
Monitoring Changes in the Intracellular Calcium Concentration and Synaptic Efficacy in the Mollusc Aplysia
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Cited by 4 •
2012
We demonstrate how changes in the intracellular free calcium concentration and synaptic efficacy can be simultaneously monitored in a ganglion preparation of Aplysia. We image intracellular calcium using a fluorescent dye, Calcium Orange, and induce and monitor synaptic transmission with sharp (intracellular) electrodes.
FAQs
Conformation determines how the atoms in a ring are arranged in three-dimensional space rather than remaining in one flat shape. Carbon-based five-membered rings can adopt envelope or half-chair forms, and these arrangements influence how bonding features are presented to surrounding molecules. As a result, conformation contributes to differences in reactivity and molecular interactions.
Nitrogen, oxygen, or sulfur can contribute to a ring’s electronic structure, allowing π electrons to become delocalized across the cyclic framework. This delocalization can provide aromatic stability, which affects the ring’s reactivity and polarity. The resulting electronic organization also helps determine how the compound interacts with other molecules in chemical and biological settings.
Ring composition, bonding, and conformation are the main structural factors identified for controlling behavior. Replacing carbon atoms with heteroatoms can change polarity and enable aromatic stabilization, while different bonding arrangements and three-dimensional shapes alter reactivity. Considering these variables together helps explain why compounds with the same overall ring size can display different molecular properties.
Changing the atoms in the loop can shift the balance among aromatic stability, polarity, conformation, and reactivity. Carbon-based systems are associated with envelope or half-chair shapes, whereas rings containing nitrogen, oxygen, or sulfur may obtain additional stabilization through delocalized π electrons. These differences provide a structural basis for tuning molecular behavior.
A general strategy is to control ring formation first and then apply chemical modifications that adjust the resulting structure. The source material emphasizes these operations as ways to tune molecular behavior and biological activity, without specifying particular reagents or reaction conditions. Researchers can therefore treat ring construction and later modification as linked stages in molecular design.
These structures occur broadly in natural products and pharmaceuticals, where their reactivity, polarity, and molecular interactions can influence biological activity. They also appear in polymers and functional materials, in which structural changes can tune molecular behavior. Their value across these areas comes from the ability to control ring formation, composition, bonding, conformation, and subsequent chemical modification.