Mills-nixon effects?

Frank, Natia L.; Siegel, Jay S.

doi:10.1016/s1046-5766(06)80007-8

Cited by 40 publications

(35 citation statements)

References 219 publications

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“…In this context, we scan the chemical realm far beyond the Mills–Nixon hypothesis, approximately saying that a small ring fused with benzene promotes the single- and double-bond alternation. A closer inspection into the ring condensation reveals that such a fusion influences an interplay between the single- and double-well potentials in benzene in many different ways. − Yet, here we focus on the C 3 symmetry fused systems yielding HOMA of the central ring close to 0. In terms of the HOMA index, this denotes the perfect bond alternation.…”

Section: Resultsmentioning

confidence: 99%

Three Queries about the HOMA Index

Dobrowolski

2019

ACS Omega

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HOMA (Harmonic Oscillator Model of Aromaticity) is a simple, successful, and widely used geometrical aromaticity index. However, HOMA can also be used as a general molecular descriptor appropriate for any type of molecule. It reaches the global maximum for benzene, whereas the potent magnetic aromaticity NICS index has no lower or upper limits. Hence, questions arise and go beyond mere differences between the geometric and magnetic aspects of aromaticity: (1) Does a molecule of aromaticity greater than that of benzene, but undisclosed by the HOMA definition, exist? (2) Can the Kekuléne cyclohexatriene moiety with HOMA = 0 exist as a part of a larger system? (3) Can the geometrical aromaticity index be defined better? Our answer to the first query is “It is not likely enough”, to the second, “Why not define HOMA using a less mysterious molecule than cyclohexatriene?”, and to the third, “It is possible to construct another fair geometrical index, but is it better for evaluating aromaticity?” To find these answers, we have studied: (1) the HOMA and NICS indices of over 50 hexahomosubstituted benzenes, (2) the HOMA, as well as EN and GEO, indices of over 100 triply fused hexasubstituted benzenes, and (3) the HOMA and new Geometrical Auxiliary Index (GAI) , of different unsaturated and saturated, aromatic and aliphatic hydrocarbons including all alkane constitutional isomers composed of up to nine carbon atoms.

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Section: Resultsmentioning

confidence: 99%

Three Queries about the HOMA Index

Dobrowolski

2019

ACS Omega

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“…[57] The origins of bond fixation have been discussed in detail elsewhere. [58] A more recent and no less spectacular application of cyclotrimerization can be found in King's synthesis of highly strained quadrannulene derivative 68 (Scheme 16), which is the smallest known member of the circulene family. [59] Its synthesis from tetrayne 67 is one of the most impressive illustrations of the sheer power of cyclotrimerization.…”

Section: Cyclotrimerizationmentioning

confidence: 99%

Extraordinary Transformations to Achieve the Synthesis of Remarkable Aromatic Compounds

Bodwell

2014

The Chemical Record

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Note from the Editor: When we walk around a sculpture, it can speak to us in many ways, sometimes quite differently from various view points. Central to Tetsuo Nozoe and the Nozoe Autograph Book project are novel aromatic compounds. Just look at nearly any page and such compounds jump out at us. We can categorize them in many ways. Their structures. Their physical properties. Their pharmacological and toxicological properties. Their commercial utilities. Their symmetry. Their size. In this essay, Graham Bodwell brings to us his analysis of the various ways in which some of the most remarkable of these compounds have been ingeniously synthesized. We are privileged to have Bodwell's vision and his sense of organization and beauty. Tetsuo Nozoe would have beamed! —Jeffrey I. Seeman Guest Editor University of Richmond Richmond, Virginia 23173, USA E‐mail: jseeman@richmond.edu

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“…The conjugated fused-ring system with two 4 n + 2π electron rings and one 4 n π electron ring indirectly has overall 4nπ electrons and does not conform to Hückelʼs rule. Whether they reflected the instability of their component antiaromatic rings has been the subject of several theoretical studies. − In this work, C1–C4 and C2–C3 of biphenylene scaffold-based compounds are obviously longer than those in cyclobutadiene (Table S3). Vollhardt has previously revealed that the presence of nitrogen accentuated the distortions induced by the cyclobutadienoid ring in biphenylene .…”

Section: Results and Discussionmentioning

confidence: 90%

Mass Spectrometry-Based Discovery of New Chemical Scaffold Rearrangement Ions: Aza-biphenylene as a Novel Potent Biradical Agent in Cancer Chemotherapy

Zhou

Cheng

et al. 2020

Anal. Chem.

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Discovery of a new drug is time-consuming, laborious, and expensive. Herein, a novel integrative strategy for discovering potential new lead compounds has been developed, which was based on the characteristics of mass spectrometry (MS). MS was used to predict the potential forced degradation products (DPs) and metabolites of drugs by electrospray ionization and collision-induced dissociation (CID). Special rearrangement ions representing unique predicted DPs and metabolites were identified. The consistency between the predicted and the measured results was proven by in vitro metabolism and forced degradation of a commercial drug, respectively. From this, new chemical scaffold rearrangement ions named (aza)-biphenylenes, as potent anticancer agents, were discovered. As a representative aza-biphenylene analogue, 2-azabiphenylene was proven in vitro to induce apoptosis and inhibit the growth of various human cancer cells in a dose-dependent manner. Surprisingly, 2-azabiphenylene exhibited the best comparable bioactivity with the positive control sorafenib, but showed significantly lower in vitro cytotoxicity than sorafenib (at least a 5-fold decrease in cytotoxicity) because it could be targeted to the tumor microenvironment at low pH. A biradical mechanism accompanied by a mitochondrion-dependent oxidative stress mechanism was proposed to explore its anticancer mechanism. The highly reactive intermediate aza-biphenylenediyl worked as an active pharmaceutical ingredient and induced apoptosis of cancer cells. This provided the basis for the potential applications of CID-induced special rearrangement ions in developing new lead compounds.

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Mills-nixon effects?

Cited by 40 publications

References 219 publications

Three Queries about the HOMA Index

Three Queries about the HOMA Index

Extraordinary Transformations to Achieve the Synthesis of Remarkable Aromatic Compounds

Mass Spectrometry-Based Discovery of New Chemical Scaffold Rearrangement Ions: Aza-biphenylene as a Novel Potent Biradical Agent in Cancer Chemotherapy

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