Table Of ContentSurvey of Volume IV/7
A monomeric calamitic liquid crystals Subvol.
1. one-ring systems a
2. two-ring systems without bridging groups
3. two-ring systems with bridging groups :
4. three-ring systems without bridging groups
5. three-ring systems with one bridging group :
6. three-ring systems with two bridging groups e
7. four-ring systems f
8. five-ring systems f
9. more than five rings f
10. metallomesogens g
11. acyclic compounds g
12. acids g
13. steroids g
B other monomeric liquid crystals
14. discotic liquid crystals h
15. polyols / sugars h
16. salts h
C polymers
17. monophilic side group polymers i
18. amphiphilic side group polymers
19. main chain polymers
20. natural polymers
21. elastomers, other polymers
Landolt-Bijrnstein
Numerical Data and Functional Relationships in Science and Technology
New Series / Editor in Chief: W. Martienssen
Group IV: Macroscopic Properties of Matter
Volume 7
Liquid Crystals
Subvolume E
Transition Temperatures and Related Properties of
Three-Ring Systems with Two Bridging Groups
V. Vi11
Edited by J. Thiem
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Editor
J. Thiem
Institut fir Organische Chemie der Universittit
Martin-Luther-King-Platz 6, D - 20146 Hamburg
Author
V.Vill
Institut tir Organische Chemie der Universittit
Martin-Luther-King-Platz 6, D - 20146 Hamburg
Preface
Volume IV/7 “Liquid Crystals” of the New Series is concerned with critically selected and
assessed data in the field of liquid crystalline compounds.
Liquid crystalline research extends physics via chemistry to the biosciences. Over the years this
borderline status generated fascinating interactions and developments both in basic and applied
research.
This currently expanding area in research and application became evident to the public recently
when the 1991-Nobel Prize in Physics was awarded to P.G. de Gennes for his contribution to
the understanding of the liquid crystalline state. Further, displays in all sorts of equipment and
machines in daily use are dependent on liquid crystalline phases and their technical
employment. An area of rapidly growing interest and studies in biochemistry, bioorganic and
organic chemistry is concerned with membrane formation, stability and molecular-molecular
interactions and recognition. Liquid crystalline phenomena are connected with detergents,
lipids, and steroids. Recently polymeric materials with liquid crystalline properties proved
valuable in “high tech” areas such as space research and household equipment.
Some data on liquid crystals appeared previously in LB 6th Edition, Vol II, part 2 in 1960 (by
W. Kast). More recent collections of data were published in tables by Deutscher Verlag fur
Grundstoffindustrie, Leipzig, in 1974 and 1982 (by D. Demus, H. Demus and H. Zaschke). By
the end of 1982 some 14000 liquid crystalline compounds were reported, 10 years later the
number has increased to approximate 50000.
The nucleus of the present volume resides in the data bank project LIQCRYST, which is almost
completed. Here all available data of liquid crystals have been collected, critically selected,
assessed and compiled including those of the above mentioned monographs and also back into
very old literature. In addition to this printed data collection the data bank LIQCRYST contains
all available physical data of liquid crystals. This allows a facile access to any substructure and
property search. The data bank LIQCRYST is expected to be available by STN Karlsruhe as an
online version, and from Springer-Verlag as an in-house version.
The present Vol. IV/7 is not published to compete with this data bank. On the contrary, the
width of individual information available there is intended to be complemented by the
advantages of printed tables. Here an overall picture of the liquid crystalline field will become
evident. This should allow ready comparison of corresponding data, and the elucidation of
structure-function relationships. Furthermore, a book generally is more easily accessible than a
file and it does not require any electronic equipment. Finally, the complete review of all the
relevant data about liquid crystals between 1850 and 1991 will be appreciated as a document in
itself.
First of all it is a particular pleasure to acknowledge the single author’s careful, deligent, and
most compctcnt work and engagement, which did not require much of an external driving force.
It should be emphasized that the Springer-Verlag, Heidelberg (Dr. R. Stumpe) and the Federal
Ministry of Science and Technology, Bonn, jointly supported the data bank project LIQCRYST
the data of which could be critically selected and assessed. Further, our own research in the
liquid crysta!line area enjoyed continuous support by the Deutsche Forschungsgemeinschaft.
Finally we want to thank the Chamber of Commerce, Hamburg and E. Merck, Darmstadt, for
providing the patent literature. Special support was obtained and is acknowledged by DipI.-
Chem. Mrs. Angela Hartwig and Mrs. Renate Poehls (Hamburg), DipI.-Phys. Alois Jandausch
and Prof. Dr. Fred Fischer (Mtinster).
Last but not least, we are grateful to the Landolt-Bornstein editorial staff in particular to Dr. H.
Seemtiller for their competent support as well as the production department for their usual high
quality completion of this volume.
Hamburg, December 1994 The Editor I
Introduction 1
Introduction
1 General remarks
1.1 Selection of data
In theset ables all thermotropico ne-componenlti quid crystalsa re included.
The scopeo f compoundsl isted in theset ablesi s much larger than that of older data collections of liquid
crystals [60K1,74D1,82Dl]. An important classo f liquid crystalline compoundst he liquid crystalline
polyols [llF1,19Gl] althoughw ell known was previously not included.
In addition somec ompoundsn ot yet proven to be liquid crystalline are incorporated,b ecauseth e proof of
mesogenicp ropertieso ften dependso n the methoda pplied.F requentlym onotropicp hasesa re not
noticed,b ut in the caseo f dopantse xtrapolatedd atam ay be as important as directly measured
temperaturesS. ometimesi t is helpful to obtain information on compoundss tudied in vain, becauseth is
prevensu nnecessaryre petitionso f experimentso r may indicatea pproachesto wards further experiments.
A large numbero f mesogenicc ompoundsw as nevers tudiedw ith respectt o their thermotropicl iquid
crystalline propertiesu ntil today. Thesei nclude surfactants,g lycolipids, lipids, steroidsa nd others.S uch
derivativesa re included if mesogenicp ropertiesw ere expecteda nd melting points or special melting
anomalies( sintering, softening)a re known.
Data are given for:
- liquid crystals
(compoundsw ith proven thermotmpic liquid crystalline properties)
- non liquid crystals with mesogenics tructuresw hich are
- chiral dopants
- dyes
- mesogenicc ompoundss tudiedw ith no liquid crystal properties
- compoundsn ot yet studied (=> clearing parameter0 )
- basic structuresf or liquid crystals (e.g. pure mesogenicg roups).
Compiled for eachc ompounda re:
- the solid-solid transitionst emperatures
- the liquid crystalline transitionst emperatures
- the heatso f transition.
Data for lyotropic liquid crystals, liquid crystal mixtures and statistic copolymers,a re not included.
1.2 Sources of data
All referencesw ith respectt o liquid crystalsw ere includedd e novo beginningw ith 18.50T. he literature
surveyso riginatedf rom CAS and Beilstein searchess, pecializedj ournals, from conferencer eportsa nd
older review articles. Incorporateda re the sourcesr efereedb y CAS until the end of 1991a nd patentsu ntil
the end of 1990.J apanesep atentsw ere only included if correspondingE uropeano r American patents
Lmdolt-Gmstein
New SeriesI Vl7b
Introduction 1
Introduction
I General remarks
1.1 Selection of data
In theset ablesa ll thermotropico ne-componenlti quid crystalsa rc included.
The scopeo f compoundsli sted in theset ablesi s much larger than that of older datac ollectionso f liquid crystals
[60K1,74D1,82Dl]. An importantc lasso f liquid crystalline compoundst he liquid crystalline polyols [llF1,19Gl]
althoughw ell known was previously not included.
In addition somec ompoundsn ot yet provent o be liquid crystalline are incorporated,b ecauseth e proof of mesogenic
propertieso ften dependso n the methoda pplied.F requentlym onotropicp hasesa re not noticed,b ut in the caseo f
dopantse xtrapolatedd ata may be as importanta s directly measuredte mperaturesS. ometimesi t is helpful to obtain
information on compoundss tudiedi n vain, becauseth is prevensu nnecessarrye petitionso f experimentso r may
indicatea pproachesto wardsf urther experimentsA. large numbero f mesogenicc ompoundsw as nevers tudiedw ith
respectt o their thermotropicl iquid crystalline propertiesu ntil today. Thesei nclude surfactants,g lycolipids, lipids,
steroidsa nd others.S uchd erivativesa re included if mesogenicp ropertiesw ere expecteda nd melting points or special
melting anomalies( sintering,s oftening)a re known.
Data are given for:
__ liquid crystals
(compoundsw ith provent hermotropicl iquid crystalline properties)
-- non liquid crystalsw ith mesogenicstructurews hich are
- chiral dopants
- dyes
- mesogenicc ompoundss tudiedw ith no liquid crystal properties
- compoundsn ot yet studied( => clearingp arameter0 )
- basic structuresf or liquid crystals( e.g. pure mesogenicg roups).
Compiledf or eachc ompounda re:
-- the solid-solid transitionst emperatures
-- the liquid crystalline transitionst emperatures
-- the heatso f transition.
Data for lyotropic liquid crystals,l iquid crystal mixtures and statistic copolymers,a re not included.
1.2 Sources of data
All referencesw ith respectt o liquid crystals were includedd e novo beginningw ith 1850.T he literatures urveys
originatedf rom GAS and Beilstein searchess, pecializedjo urnals, from conferencer eportsa nd older review articles.
Incorporateda re the sourcesr efereedb y GAS until the end of 1991a nd patentsu ntil the end of 1990.J apanese
patentsw ere only includedi f correspondingE uropeano r Americanp atentse xisted.T he most importants ourcesf or
theset ablesw ere taken from journals, patents,c onferencep roceedingsm, onographsa nd Germand octoral theses.
Landolt-Bijmstein
New Series lV/7e.
2 Introduction
1.3 Arrangement of data
Liquid crystal researchis an interdisciplenarya rea.T hus,a n arrangemenot f compoundsb aseds olely on physical
aspectsc ould hardly satisfy the chemist.H e would then find smecticp henyl benzoatesn ext to smectica lkyl
glycosidesb ut could not deducefromt his wheret o incorporatea novel liquid crystallinec ompound.O n the other
hand,a n arrangemenfto llowing purely chemicala spectsc ould hardly satisfy the physicist.H e would find columnar-
discotic ands mectici nositols in one table,a nd in caseo f a searchf or certainp ropertiest he whole materialw ould
havet o be scannedf rom the beginningt o the end.
Therefore,t he arrangemenwt as selecteda ccordingt o a stepwised ominanceo f chemicala nd physical principles.F irst
therei s a chemicalc lassificationi nto monomericandp olymericc ompoundsT. he most importantc lasso f monomeric
compoundsis classifiedf ollowing physicalp rinciplesi nto calamitic and discotic liquid crystals.T hesec lassesin turn
are subdivideda ccordingt o chemical-physicaal spectsin to amphiphilica nd monophilic liquid crystals.T he largest
classo f monophilicc alamitesi s agains ubdivideda ccordingt o chemicala spectsin to simple calamites,a cidsa nd
steroids.
The assignmenot f thesec lasseso f compoundsto the individual systemsp roceedsa ccordingt o formal chemical
aspectss ucha s the numbera nd successiono f fragments:
Orderp rinciplesf or mesogenicg roups( systems):
1. numbero f rings
2. numbero f bridging groups
3. priority of rings
4. priority of bridging groups
5. priority of side groups
Priority of rings:
3.1. benzene
3.2. substitutedb enzenes
isomersc deuteratedb enzenes< halogen-substitutebde nzenes< alkyl-substitutedb enzenes
3.3. six-membereda romaticr ings
3.4. other monocyclica romaticr ings
3.5. cyclohexane
3.6. alicyclic rings
3.7. complexr ing systems
3.8. metalc omplexes
Priority of side gmups:
5.1. compoundsw ithout terminal alkyl chains
5.2. compoundsw ith one temlinal alkyl chain
5.3. compoundsw ith two terminal alkyl chains
The easiesta pproachf or a compounds earchi s given in the systemo verview. Here only structurald epictionso f
mesogenicg roupsa nd the correspondingp agesa re included.
Land&-BSmtein
New Series IV/7e
Iutroduction 3
1.4 Continuation
A future updateo f this seriesb y supplemenvt olumesi s intended.N ew supplemenvt olumesw ill incorporatet he
materialo f previouss upplemenvt olumes,a nd this allows the usero f the seriest o find updatedm ateriala lways in two
volumes.
2 Chemical structures
Within recenty earst he numbero f liquid crystals reportedh asi ncreasede xponentially.T hus, registrationa nd
assessmenotf all compoundsis only feasablee mployingc omputer-aideda pproachesI.n contrast,t he previously
classificationo f the compoundsa ccordingt o purely synthetica spects[ 60K1,74D1,82Dl] is impossiblet oday. On the
other handa classificationo f compoundsfo llowing just the connectivityo f atoms[ CAS-Online,B eilstein-Online]i s
difficult to display in tables.T herefore,t he documentationo f liquid crystalsr equireda novel fragment-orientedd ata
bank system,w hich is predominantlyb asedo n the scientific languageu seda mongr esearcherisn the liquid crystal
field.
An unequivocalp resentationa nd classificationo f all compoundso n a mores ophisticatedle vel than the connectivities
of atoms is required,a s shown below.
link bridge ring terminal group
I -IIn
side group mesogenic group side group
L R
A liquid crystalline compoundi s subdividedi nto the mesogenic group and the side groups. The mesogenicg roup is
subdividedi nto the fragmentsr ings and bridges. The side groupsa re subdividedi n links and termhl groups.
In addition, therea re somes pecific fragmentss ucha s discs in caseo f monophilicd iscotics,p olymer backbones in
the caseo f side group polymers,s teroids etc.
Eachl iquid crystalline compoundi s divided into a linear sequenceo f fragments.F ragmentsa re connectedb y single
bonds.S omef ragmentsc an bind on one side a numbero f identicalf ragments.T heset ypesa re usedf or discotics,
twins and forked compounds.
Land&-BGrnsteia
New SeriesI V/7e
