Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: UMLS:C0847097 (
acidity
)
15,165
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
The subfamily Lamioideae (Lamiaceae) comprises ten tribes, of which only Stachydeae and Synandreae include New World members. Previous studies have investigated the phylogenetic relationships among the members of Synandreae based on plastid and nuclear ribosomal DNA loci. In an effort to re-examine the phylogenetic relationships within Synandreae, the current study incorporates data from four low-copy nuclear loci, PHOT1, PHOT2, COR, and
PPR
. Our results confirm previous studies based on chloroplast and nuclear ribosomal markers in supporting the monophyly of tribe Synandreae, as well as sister relationships between Brazoria and Warnockia, and between that pair of genera and a monophyletic Physostegia. However, we observe incongruence in the relationships of Macbridea and Synandra. The placement of Synandreae within Lamioideae is poorly resolved and incongruent among different analyses, and the sister group of Synandreae remains enigmatic. Comparison of the colonization and migration patterns corroborates a single colonization of the New World by Synandreae during the Late Miocene/Tortonian age. This is in contrast to the only other lamioid tribe that includes New World members, Stachydeae, which colonized the New World at least twice-during the mid-Miocene and Pliocene. Edaphic conditions and intolerance of soil
acidity
may be factors that restricted the distribution of most genera of Synandreae to southeastern and south-central North America, whereas polyploidy could have increased the colonizing capability of the more wide-ranging genus, Physostegia.
...
PMID:Evolutionary relationships within the lamioid tribe Synandreae (Lamiaceae) based on multiple low-copy nuclear loci. 2754 37
Triflate salts of trications [(bipy)
2
E]
3+
([
6E
][OTf]
3
) and [(tbbipy)
2
E]
3+
([
6'E
][OTf]
3
) (bipy = 2,2'-bipyridine, tbbipy = 4,4'-di-
t
butyl-2,2'-bipyridine; E = P, As, Sb, Bi) have been synthesized and comprehensively characterized. The unique molecular and electronic structures of this new class of complexes involving pnictogen Lewis acids has been assessed in the solid, solution and gas phases to reveal systematic variations in metric parameters, ligand lability and charge concentration. While the Lewis
acidity
of E
3+
has the trend E = Bi < Sb < As < P as determined by gas-phase calculations and
1
H NMR spectroscopy, the Lewis
acidity
of [
6E
]
3+
has the trend E = P < As < Sb < Bi according to gas-phase calculations. Derivatives of [
6'E
][OTf]
3
(E = P, As) are latent sources of E(OTf)
3
as demonstrated by their reactions with dmap, which give the corresponding derivatives of [(dmap)
3
E][OTf]
3
. The highly oxidizing nature of P(OTf)
3
and As(OTf)
3
is evidenced in reactions of [
6'E
][OTf]
3
(E = P, As) with phosphines, which give E
I
-containing monocations [(R
3
P)
2
E]
1+
and oxidatively coupled dications [R
3
PPR
3
]
2+
, illustrating new P-P and P-As bond forming strategies. Cations [
6'E
]
3+
(E = P, As) are C-H bond activating agents that dehydrogenate 1,4-cyclohexadiene, with higher activity observed for E = P. Combinations of [
6'E
]
3+
and
t
Bu
3
P activate H
2
and D
2
under mild conditions, evidencing frustrated Lewis pair activity. Oxidation of [
6'P
][OTf]
3
with SO
2
Cl
2
gives [(tbbipy)
2
PCl
2
][OTf]
3
, containing a P
V
-trication, but there is no evidence of the analogous reaction with [
6'As
][OTf]
3
. The observations highlight new directions in the chemistry of highly charged cations and reveal a rich reactivity for p-block triflates E(OTf)
3
, which can be accessed through derivatives of [
6E
][OTf]
3
and [
6'E
][OTf]
3
.
...
PMID:Bipyridine complexes of E
3+
(E = P, As, Sb, Bi): strong Lewis acids, sources of E(OTf)
3
and synthons for E
I
and E
V
cations. 3012 60
