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  2. Pi bond - Wikipedia

    en.wikipedia.org/wiki/Pi_bond

    A typical triple bond, for example in acetylene (HC≡CH), consists of one sigma bond and two pi bonds in two mutually perpendicular planes containing the bond axis. Two pi bonds are the maximum that can exist between a given pair of atoms. Quadruple bonds are extremely rare and can be formed only between transition metal atoms, and consist of ...

  3. Pi-interaction - Wikipedia

    en.wikipedia.org/wiki/Pi-interaction

    In chemistry, π-effects or π-interactions are a type of non-covalent interaction that involves π systems.Just like in an electrostatic interaction where a region of negative charge interacts with a positive charge, the electron-rich π system can interact with a metal (cationic or neutral), an anion, another molecule and even another π system. [1]

  4. Chromophore - Wikipedia

    en.wikipedia.org/wiki/Chromophore

    In a conjugated pi-system, electrons are able to capture certain photons as the electrons resonate along a certain distance of p-orbitals - similar to how a radio antenna detects photons along its length. Typically, the more conjugated (longer) the pi-system is, the longer the wavelength of photon can be captured.

  5. Chemical bond - Wikipedia

    en.wikipedia.org/wiki/Chemical_bond

    Two p-orbitals forming a pi-bond. A double bond has two shared pairs of electrons, one in a sigma bond and one in a pi bond with electron density concentrated on two opposite sides of the internuclear axis. A triple bond consists of three shared electron pairs, forming one sigma and two pi bonds. An example is nitrogen.

  6. Cation–π interaction - Wikipedia

    en.wikipedia.org/wiki/Cation–π_interaction

    Bonding energies are significant, with solution-phase values falling within the same order of magnitude as hydrogen bonds and salt bridges. Similar to these other non-covalent bonds, cation–π interactions play an important role in nature, particularly in protein structure, molecular recognition and enzyme catalysis. The effect has also been ...

  7. Isoelectric point - Wikipedia

    en.wikipedia.org/wiki/Isoelectric_point

    The isoelectric point (pI, pH(I), IEP), is the pH at which a molecule carries no net electrical charge or is electrically neutral in the statistical mean. The standard nomenclature to represent the isoelectric point is pH(I). [1] However, pI is also used. [2] For brevity, this article uses pI.

  8. Pi-stacking - Wikipedia

    en.wikipedia.org/wiki/Pi-stacking

    In chemistry, pi stacking (also called π–π stacking) refers to the presumptively attractive, noncovalent pi interactions between the pi bonds of aromatic rings, because of orbital overlap. [1] According to some authors direct stacking of aromatic rings (the "sandwich interaction") is electrostatically repulsive.

  9. Mesomeric effect - Wikipedia

    en.wikipedia.org/wiki/Mesomeric_effect

    In chemistry, the mesomeric effect (or resonance effect) is a property of substituents or functional groups in a chemical compound.It is defined as the polarity produced in the molecule by the interaction of two pi bonds or between a pi bond and lone pair of electrons present on an adjacent atom. [1]