1 a. Explain why compound with conjugated systems can fluoresce. b. Why is tryptophan more fluorescent...
1
a. Explain why compound with conjugated systems can fluoresce.
b. Why is tryptophan more fluorescent than tyrosine and phenylalanine?
Homework Answers
Solution:
a) In the conjugated systems, the ground states and excited states of the electrons are closer in energy than for
non-conjugated systems. Therefore, a lower energy light is needed to excite electrons in conjugated systems, which means that
lower energy light is absorbed by conjugated systems. Hence, conjugated systems can fluoresce.
b) Tryptophan is significantly more fluorescent than tyrosine and phenylalanine because of its greater absorptivity, higher
quantum yield, and resonance energy transfer than tyrosine and phenylalanine. Its fluorescent properties are solvent dependent,
therefore, the spectrum shifts to shorter wavelengths and increases in intensity as the polarity of the solvent decreases.
Add Answer to:
1
a. Explain why compound with conjugated systems can
fluoresce.
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9. Aromatic residues, such as tyrosine, phenylalanine, and tryptophan, are common in a polypeptide. Their side...
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(c) Tryptophan can absorb UV light around 280 nm and fluoresces around 355 nm. Explain why...
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ch 21 5g Visited For each of the species below, identify any cyclic conjugated system, then:...
ch 21
5g Visited For each of the species below, identify any cyclic conjugated system, then: A. Determine the number of electrons in a system of cyclic conjugation (zero if no cyclic conjugation) B. Specify whether the species is "a"-aromatic, "aa"-anti-aromatic, or "na"-non-aromatic (neither aromatic nor anti-aromatic). (Presume rings to be planar unless structure obviously prevents planarity. If there is more than one conjugated ring count electrons in the largest.) 1. A.Electrons in a cyclic conjugated system B.The compound is...
ch. 21 [Review Topics [References] For each of the species below, identify any cyclic conjugated system,...
ch. 21
[Review Topics [References] For each of the species below, identify any cyclic conjugated system, then: A. Determine the number of electrons in a system of cyclic conjugation (zero if no cyclic conjugation). B. Specify whether the species is "a"-aromatic, "aa" anti-aromatic, or "na"-non-aromatic (neither aromatic nor anti-aromatic). (Presume rings to be planar unless structure obviously prevents planarity. If there is more than one conjugated ting, count electrons in th largest.) 1. A.Electrons in a cyclic conjugated system. B.The...
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15. Circle one of the following charged compounds which is most stable. (3 Points) Which is the stronger influence for your choice? a) Resonance or b) Induction (hyperconjugation)? (2 Points)
9. Aromatic residues, such as tyrosine, phenylalanine, and tryptophan, are common in a polypeptide. Their side chains have an aromatic ring, which is a resonant structure composed of TT bonds. When a cation in the solution is closed to this aromatic structure, it can polarize the ring to form a dipole. Will this cation- aromatic ring interaction be stable in water or non-polar solvent? Briefly explain why. (10 pts)
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ch 21
5g Visited For each of the species below, identify any cyclic conjugated system, then: A. Determine the number of electrons in a system of cyclic conjugation (zero if no cyclic conjugation) B. Specify whether the species is "a"-aromatic, "aa"-anti-aromatic, or "na"-non-aromatic (neither aromatic nor anti-aromatic). (Presume rings to be planar unless structure obviously prevents planarity. If there is more than one conjugated ring count electrons in the largest.) 1. A.Electrons in a cyclic conjugated system B.The compound is...
ch. 21
[Review Topics [References] For each of the species below, identify any cyclic conjugated system, then: A. Determine the number of electrons in a system of cyclic conjugation (zero if no cyclic conjugation). B. Specify whether the species is "a"-aromatic, "aa" anti-aromatic, or "na"-non-aromatic (neither aromatic nor anti-aromatic). (Presume rings to be planar unless structure obviously prevents planarity. If there is more than one conjugated ting, count electrons in th largest.) 1. A.Electrons in a cyclic conjugated system. B.The...
Could anyone explain why the first compound is more stable than
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