Macrocyclic Polyradicaloids with Unusual Super-ring Structure and Global Aromaticity

Chunchen Liu, María Eugenia Sandoval-Salinas, Yongseok Hong, Tullimilli Y. Gopalakrishna, Hoa Phan, Naoki Aratani, Tun Seng Herng, Jun Ding, Hiroko Yamada, Dongho Kim, David Casanova, Jishan Wu

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

π-Conjugated molecules with an annulene-within-an-annulene (AWA) super-ring structure have been pursued by chemists for a long time but with limited success. Here, we report the synthesis of two stable cyclopenta-ring-fused oligo(m-phenylene) macrocycles, 8MC-M and 10MC-M, both showing moderate polyradical character. The octaradicaloid 8MC-M exhibits a [24]annulene-within-[32]annulene structure, which is globally aromatic despite the fact that it possesses 4n π-electrons. Theoretical analyses reveal that the π-electrons in the inner and outer rings follow Baird's rule such that both are triplet biradicals, and overall the molecule is a ground-state spin singlet. The decaradicaloid 10MC-M also possesses a super-aromatic AWA structure with 30 and 40 π-electrons in the inner and outer rings, respectively. However, it has a triplet ground state with a singlet inner ring satisfying Hückel's rule and a triplet outer ring following Baird's rule. Therefore, molecules with a decoupled AWA super-ring structure are eventually attained and also show unusual global aromaticity. Organic opto-electronic and magnetic materials play an important role in future affordable electronics and clean energy, and aromaticity is one of the most important concepts that determine their physical and material properties. Over the past nine decades, Hückel's rule and Baird's rule have been developed to describe the (anti)aromaticity of monocyclic π-conjugated molecules. For polycyclic π-conjugated systems, localized aromaticity usually dominates, and there is almost no report of global aromaticity for benzenoid polycyclic hydrocarbons. In this work, we experimentally obtained two hydrocarbon-based macrocyclic polyradicaloids, which show a long-sought-after annulene-within-an-annulene super-ring structure and very unusual global aromaticity. Both Hückel's rule and Baird's rule can be followed for these polyradicaloids. Our study gives some new insight into the unique global aromaticity in polycyclic π-conjugated molecules. Wu and colleagues describe the challenging synthesis and physical characterization of a macrocyclic octaradicaloid and decaradicaloid. They exhibit the long-sought-after “annulene-within-an-annulene” super-ring structure and unusual global aromaticity with individual inner and outer rings following Hückel's rule in the singlet state and Baird's rule in the triplet state, respectively.

Original languageEnglish
Pages (from-to)1586-1595
Number of pages10
JournalChem
Volume4
Issue number7
DOIs
Publication statusPublished - 2018 Jul 12

Fingerprint

Electrons
electron
Molecules
Cyclic Hydrocarbons
Ground state
Hydrocarbons
hydrocarbon
Magnetic materials
Materials properties
Electronic equipment
Physical properties
energy
electronics
material
polycyclic hydrocarbon

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Biochemistry
  • Environmental Chemistry
  • Chemical Engineering(all)
  • Biochemistry, medical
  • Materials Chemistry

Cite this

Liu, C., Sandoval-Salinas, M. E., Hong, Y., Gopalakrishna, T. Y., Phan, H., Aratani, N., ... Wu, J. (2018). Macrocyclic Polyradicaloids with Unusual Super-ring Structure and Global Aromaticity. Chem, 4(7), 1586-1595. https://doi.org/10.1016/j.chempr.2018.03.020
Liu, Chunchen ; Sandoval-Salinas, María Eugenia ; Hong, Yongseok ; Gopalakrishna, Tullimilli Y. ; Phan, Hoa ; Aratani, Naoki ; Herng, Tun Seng ; Ding, Jun ; Yamada, Hiroko ; Kim, Dongho ; Casanova, David ; Wu, Jishan. / Macrocyclic Polyradicaloids with Unusual Super-ring Structure and Global Aromaticity. In: Chem. 2018 ; Vol. 4, No. 7. pp. 1586-1595.
@article{e7f8c9c9dbb14863a7ba6958da6485b2,
title = "Macrocyclic Polyradicaloids with Unusual Super-ring Structure and Global Aromaticity",
abstract = "π-Conjugated molecules with an annulene-within-an-annulene (AWA) super-ring structure have been pursued by chemists for a long time but with limited success. Here, we report the synthesis of two stable cyclopenta-ring-fused oligo(m-phenylene) macrocycles, 8MC-M and 10MC-M, both showing moderate polyradical character. The octaradicaloid 8MC-M exhibits a [24]annulene-within-[32]annulene structure, which is globally aromatic despite the fact that it possesses 4n π-electrons. Theoretical analyses reveal that the π-electrons in the inner and outer rings follow Baird's rule such that both are triplet biradicals, and overall the molecule is a ground-state spin singlet. The decaradicaloid 10MC-M also possesses a super-aromatic AWA structure with 30 and 40 π-electrons in the inner and outer rings, respectively. However, it has a triplet ground state with a singlet inner ring satisfying H{\"u}ckel's rule and a triplet outer ring following Baird's rule. Therefore, molecules with a decoupled AWA super-ring structure are eventually attained and also show unusual global aromaticity. Organic opto-electronic and magnetic materials play an important role in future affordable electronics and clean energy, and aromaticity is one of the most important concepts that determine their physical and material properties. Over the past nine decades, H{\"u}ckel's rule and Baird's rule have been developed to describe the (anti)aromaticity of monocyclic π-conjugated molecules. For polycyclic π-conjugated systems, localized aromaticity usually dominates, and there is almost no report of global aromaticity for benzenoid polycyclic hydrocarbons. In this work, we experimentally obtained two hydrocarbon-based macrocyclic polyradicaloids, which show a long-sought-after annulene-within-an-annulene super-ring structure and very unusual global aromaticity. Both H{\"u}ckel's rule and Baird's rule can be followed for these polyradicaloids. Our study gives some new insight into the unique global aromaticity in polycyclic π-conjugated molecules. Wu and colleagues describe the challenging synthesis and physical characterization of a macrocyclic octaradicaloid and decaradicaloid. They exhibit the long-sought-after “annulene-within-an-annulene” super-ring structure and unusual global aromaticity with individual inner and outer rings following H{\"u}ckel's rule in the singlet state and Baird's rule in the triplet state, respectively.",
author = "Chunchen Liu and Sandoval-Salinas, {Mar{\'i}a Eugenia} and Yongseok Hong and Gopalakrishna, {Tullimilli Y.} and Hoa Phan and Naoki Aratani and Herng, {Tun Seng} and Jun Ding and Hiroko Yamada and Dongho Kim and David Casanova and Jishan Wu",
year = "2018",
month = "7",
day = "12",
doi = "10.1016/j.chempr.2018.03.020",
language = "English",
volume = "4",
pages = "1586--1595",
journal = "Chem",
issn = "2451-9294",
publisher = "Elsevier Inc.",
number = "7",

}

Liu, C, Sandoval-Salinas, ME, Hong, Y, Gopalakrishna, TY, Phan, H, Aratani, N, Herng, TS, Ding, J, Yamada, H, Kim, D, Casanova, D & Wu, J 2018, 'Macrocyclic Polyradicaloids with Unusual Super-ring Structure and Global Aromaticity', Chem, vol. 4, no. 7, pp. 1586-1595. https://doi.org/10.1016/j.chempr.2018.03.020

Macrocyclic Polyradicaloids with Unusual Super-ring Structure and Global Aromaticity. / Liu, Chunchen; Sandoval-Salinas, María Eugenia; Hong, Yongseok; Gopalakrishna, Tullimilli Y.; Phan, Hoa; Aratani, Naoki; Herng, Tun Seng; Ding, Jun; Yamada, Hiroko; Kim, Dongho; Casanova, David; Wu, Jishan.

In: Chem, Vol. 4, No. 7, 12.07.2018, p. 1586-1595.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Macrocyclic Polyradicaloids with Unusual Super-ring Structure and Global Aromaticity

AU - Liu, Chunchen

AU - Sandoval-Salinas, María Eugenia

AU - Hong, Yongseok

AU - Gopalakrishna, Tullimilli Y.

AU - Phan, Hoa

AU - Aratani, Naoki

AU - Herng, Tun Seng

AU - Ding, Jun

AU - Yamada, Hiroko

AU - Kim, Dongho

AU - Casanova, David

AU - Wu, Jishan

PY - 2018/7/12

Y1 - 2018/7/12

N2 - π-Conjugated molecules with an annulene-within-an-annulene (AWA) super-ring structure have been pursued by chemists for a long time but with limited success. Here, we report the synthesis of two stable cyclopenta-ring-fused oligo(m-phenylene) macrocycles, 8MC-M and 10MC-M, both showing moderate polyradical character. The octaradicaloid 8MC-M exhibits a [24]annulene-within-[32]annulene structure, which is globally aromatic despite the fact that it possesses 4n π-electrons. Theoretical analyses reveal that the π-electrons in the inner and outer rings follow Baird's rule such that both are triplet biradicals, and overall the molecule is a ground-state spin singlet. The decaradicaloid 10MC-M also possesses a super-aromatic AWA structure with 30 and 40 π-electrons in the inner and outer rings, respectively. However, it has a triplet ground state with a singlet inner ring satisfying Hückel's rule and a triplet outer ring following Baird's rule. Therefore, molecules with a decoupled AWA super-ring structure are eventually attained and also show unusual global aromaticity. Organic opto-electronic and magnetic materials play an important role in future affordable electronics and clean energy, and aromaticity is one of the most important concepts that determine their physical and material properties. Over the past nine decades, Hückel's rule and Baird's rule have been developed to describe the (anti)aromaticity of monocyclic π-conjugated molecules. For polycyclic π-conjugated systems, localized aromaticity usually dominates, and there is almost no report of global aromaticity for benzenoid polycyclic hydrocarbons. In this work, we experimentally obtained two hydrocarbon-based macrocyclic polyradicaloids, which show a long-sought-after annulene-within-an-annulene super-ring structure and very unusual global aromaticity. Both Hückel's rule and Baird's rule can be followed for these polyradicaloids. Our study gives some new insight into the unique global aromaticity in polycyclic π-conjugated molecules. Wu and colleagues describe the challenging synthesis and physical characterization of a macrocyclic octaradicaloid and decaradicaloid. They exhibit the long-sought-after “annulene-within-an-annulene” super-ring structure and unusual global aromaticity with individual inner and outer rings following Hückel's rule in the singlet state and Baird's rule in the triplet state, respectively.

AB - π-Conjugated molecules with an annulene-within-an-annulene (AWA) super-ring structure have been pursued by chemists for a long time but with limited success. Here, we report the synthesis of two stable cyclopenta-ring-fused oligo(m-phenylene) macrocycles, 8MC-M and 10MC-M, both showing moderate polyradical character. The octaradicaloid 8MC-M exhibits a [24]annulene-within-[32]annulene structure, which is globally aromatic despite the fact that it possesses 4n π-electrons. Theoretical analyses reveal that the π-electrons in the inner and outer rings follow Baird's rule such that both are triplet biradicals, and overall the molecule is a ground-state spin singlet. The decaradicaloid 10MC-M also possesses a super-aromatic AWA structure with 30 and 40 π-electrons in the inner and outer rings, respectively. However, it has a triplet ground state with a singlet inner ring satisfying Hückel's rule and a triplet outer ring following Baird's rule. Therefore, molecules with a decoupled AWA super-ring structure are eventually attained and also show unusual global aromaticity. Organic opto-electronic and magnetic materials play an important role in future affordable electronics and clean energy, and aromaticity is one of the most important concepts that determine their physical and material properties. Over the past nine decades, Hückel's rule and Baird's rule have been developed to describe the (anti)aromaticity of monocyclic π-conjugated molecules. For polycyclic π-conjugated systems, localized aromaticity usually dominates, and there is almost no report of global aromaticity for benzenoid polycyclic hydrocarbons. In this work, we experimentally obtained two hydrocarbon-based macrocyclic polyradicaloids, which show a long-sought-after annulene-within-an-annulene super-ring structure and very unusual global aromaticity. Both Hückel's rule and Baird's rule can be followed for these polyradicaloids. Our study gives some new insight into the unique global aromaticity in polycyclic π-conjugated molecules. Wu and colleagues describe the challenging synthesis and physical characterization of a macrocyclic octaradicaloid and decaradicaloid. They exhibit the long-sought-after “annulene-within-an-annulene” super-ring structure and unusual global aromaticity with individual inner and outer rings following Hückel's rule in the singlet state and Baird's rule in the triplet state, respectively.

UR - http://www.scopus.com/inward/record.url?scp=85046167567&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85046167567&partnerID=8YFLogxK

U2 - 10.1016/j.chempr.2018.03.020

DO - 10.1016/j.chempr.2018.03.020

M3 - Article

AN - SCOPUS:85046167567

VL - 4

SP - 1586

EP - 1595

JO - Chem

JF - Chem

SN - 2451-9294

IS - 7

ER -

Liu C, Sandoval-Salinas ME, Hong Y, Gopalakrishna TY, Phan H, Aratani N et al. Macrocyclic Polyradicaloids with Unusual Super-ring Structure and Global Aromaticity. Chem. 2018 Jul 12;4(7):1586-1595. https://doi.org/10.1016/j.chempr.2018.03.020