Sorry, I did not realised that. (I should have changed subject of the original post)
Yes, we are not saying different things. Stefano Le 2018-09-19 17:06, Frank von Delft a écrit : > Okay. The original poster asked about hydrogen bonds and electrostatic > interactions. That's what I was referring to when I mentioned "enthalpic > interactions". > > And I think you're saying the same thing - which is cool. > > On 19/09/2018 15:06, Stefano Trapani wrote: >> Hi Frank > > I mean that, in my opinion, the term "enthalpic interaction" is >> not > appropriate to describe the hydrophobic effect, since the latter is > >> mainly driven by changes in the (system) entropy, not enthalpy. > > Table1 >> of the cited paper reports the thermodynamic functions for > transferring >> some nonpolar solutes from a few organic solvents to > water. The author >> says that: "The data collected in Table 1 clearly > show that the >> thermodynamic barrier to the solution process is > entropic rather than >> enthalpic". > > Also, after a brief description of two theoretical models >> (the > cavity-based model and the clathrate cage model) the author states: > >> "It is important to point out that both the cavity-based model and > the >> clathrate cage model rest upon the fact that the hydrophobic > effect is >> entropy, not enthalpy driven. The models differ only in how > they explain >> the source of the entropy loss." > > Best > > Stefano > > > > Le 2018-09-19 >> 14:41, Frank von Delft a écrit : >> >> Hi Stefano - could you elaborate? >> >> Certainly the medicinal chemists >> >> go on a great deal about how >> deltaH balances deltaS and how it's >> >> bloody hard to know what is >> what even when you try to measure it. >> >> Which is what that abstract >> also goes on about. >> >> >> >> On >> >> 19/09/2018 10:54, Stefano Trapani wrote: >>> >>> Le 2018-09-19 11:59, >> >> Frank von Delft a écrit : >>> >>> I believe medicinal chemists do indeed >> >> talk about "enthalpic >>> interactions". Frank >>> >>> Not a good choice >> >> either (à mon avis ...) >>> >>> >>> >>> >>> >>> The Real Reason Why Oil >> >> and Water Don't Mix >>> >>> Todd P. Silverstein Journal of Chemical >> >> Education *1998* /75/ >>> (1), 116 >>> >>> DOI: 10.1021/ed075p116 >>> >>> >> >> https://pubs.acs.org/doi/abs/10.1021/ed075p116 [1] >>> >>> >>> Stefano >> >> >>> >>> >>> >>> On 19/09/2018 10:40, Stefano Trapani wrote: >>> >>> Le >> >> 2018-09-18 19:31, Daniel M. Himmel, Ph. D. a écrit : >>> >>> (where >> >> hydrophobic interactions result from van der Waals forces >>> in an aqueous environment). >>> >>> Hi >>> >>> I am not sure that, if one is to give a concise definition of >>> hydrophobic "interactions", this would be a convenient one, >>> because it may lead someone to identify vdW forces as the main >>> factor that maintains apolar aggregated molecules together in >>> aqueous environment. I have seen many students (and PhD's) >>> believing to the equality: hydrophobic 'forces'=vdW forces (and >>> not understanding, for example, that the side chains of a Ser and >>> an Ile can also establish vdW interactions). >>> >>> It is true that apolar groups that aggregate establish van der >>> Waals interactions (like any molecule in contact with another >>> one) but these microscopic (real) forces are not (as far as I >>> know) the main reason of aggregation in aqueous environment. >>> >>> The hydrophobic effect seem to be of a mainly entropic nature >>> (and it has much more to do with hydrogen bonds than van der >>> Waals forces): >>> >>> https://en.wikipedia.org/wiki/Hydrophobic_effect#Cause [2] >>> >>> https://en.wikipedia.org/wiki/Entropic_force#Hydrophobic_force [3] >>> >>> Being mainly of an entropic nature, hydrophobic "contacts" are >>> not the direct result of real microscopic "forces" that act >>> between apolar groups. The terms "forces" and "interactions" in >>> widely used expressions like "hydrophobic forces" and >>> "hydrophobic interactions" are somehow misleading. >>> >>> Best >>> >>> --- Stefano Trapani >>> >>> Maître de Conférences >>> http://www.cbs.cnrs.fr/index.php/fr/personnel?PERS=Stefano%20Trapani [4] >>> >>> ------------------------------------- >>>> Centre de Biochimie Structurale (CBS) 29 rue de Navacelles 34090 >>> >>>> MONTPELLIER Cedex, France >>> >>> Tel : +33 (0)4 67 41 77 29 Fax : +33 >>>> (0)4 67 41 79 13 >>> ------------------------------------- Université de >>>> Montpellier >>> CNRS UMR 5048 INSERM UMR 1054 >>> >>>> ------------------------------------- >>> >>> >>> -- This message has been >>>> scanned for viruses and dangerous >>> content by *MailScanner* >>>> <http://www.mailscanner.info/> [5], and is >>> believed to be clean. >>>> ------------------------- >>> >>> To unsubscribe from the CCP4BB list, >>>> click the following link: >>> >>>> https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 [6] >>> >>> >>>> >>> >>> -- This message has been scanned for viruses and dangerous >>> >>>> content by *MailScanner* <http://www.mailscanner.info/> [5], and is >>> >>>> believed to be clean. >>> >>> >>> -- This message has been scanned for >>>> viruses and dangerous >>> content by *MailScanner* >>>> <http://www.mailscanner.info/> [5], and is >>> believed to be clean. >> >> >>>> >> -- This message has been scanned for viruses and dangerous content >> by *MailScanner* <http://www.mailscanner.info/> [5], and is believed to >> be clean. > > -- This message has been scanned for viruses and dangerous content by > *MailScanner* <http://www.mailscanner.info/> [5], and is believed to be > clean. > > -- > This message has been scanned for viruses and > dangerous content by MAILSCANNER [5], and is > believed to be clean. Links: ------ [1] https://pubs.acs.org/doi/abs/10.1021/ed075p116 [2] https://en.wikipedia.org/wiki/Hydrophobic_effect#Cause [3] https://en.wikipedia.org/wiki/Entropic_force#Hydrophobic_force [4] http://www.cbs.cnrs.fr/index.php/fr/personnel?PERS=Stefano%20Trapani [5] http://www.mailscanner.info/ [6] https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1
