ABSTRACT
Many BF2 complexes of heteroaromatics are well known for their dual-state emission (DSE) properties. However, AIE and ACQ effects have also been observed in certain cases. To date, no rational explanations have been proposed for these uncommon photoluminescence (PL) behaviours. The current research prepared four BF2 complexes of N-benzoyl 2-aminobenzothiazoles with diversified photoluminescence (PL) properties as model compounds and utilized quantum chemical calculation tools to address this issue. Theoretical calculations revealed that the electron-donating groups (EDGs) at the para-position of the exocyclic phenyl ring exert significant influence on their ground-state electronic structures and vertical excitation features. Potential energy curve (PEC) analysis showed that the exocyclic phenyl ring and NMe2 could not function as effective rotors due to elevated energy barriers. Only the NPh2 of BFBB-3 could spontaneously rotate â¼60° to induce the formation of an emissive twisted intramolecular charge transfer (TICT) state. The two-channel model involving both vibronic relaxation and S0/S1 surface crossing revealed that the drastic narrowing of the S1/S0 energy gap in the region approaching minimun energy conical intersection (MECI) led to the generation of a dark state in BFBB-1. The small energy barrier to access the dark-state region makes the resulting fast internal conversion a competitive channel for excited-state deactivation. In contrast, the presence of EDGs in BFBB-2 and 4 inhibits this pathway, thereby resulting in intense fluorescence emissions in solution. In addition, crystallographic analysis illustrated that the F atoms perpendicular to the polyheterocycle promoted a slipped face-to-face packing mode and enhanced intermolecular interactions. The efficiencies of their solid-state emissions are mainly affected by the degree of π-π overlaps.
ABSTRACT
An efficient P(V)-N activation approach for the synthesis of cytidine diphosphate choline (CDP-choline) and related ribo- and deoxyribonucleotide analogs has been established.
Subject(s)
Cytidine Diphosphate Choline/analogs & derivatives , Cytidine Diphosphate Choline/chemistry , Cytidine Diphosphate Choline/chemical synthesisABSTRACT
The mol-ecule of the title compound, C(18)H(19)N(3)O, displays a trans configuration with respect to the C=N double bond. The dihedral angle between the planes of the two benzene rings is 2.62â (11)°. A strong intra-molecular O-Hâ¯N hydrogen bond stabilizes the mol-ecular conformation.
ABSTRACT
Treatment of [Et(4)N](2)[(edt)(2)Mo(2)S(2)(µ-S)(2)] (edt = ethane-dithio-l-ate) with two equivalents of Ag(CH(3)CN)(4)ClO(4) in the presence of bis-(diphenyl-phosphino)methane (dppm) ligand gives rise to the title tetra-nuclear cluster, [Ag(2)Mo(2)(C(2)H(4)S(2))(2)S(4)(C(25)H(22)P(2))(2)]·3C(3)H(7)NO. The complex mol-ecule and one of the dimethyl-formamide (DMF) solvent mol-ecules occupy special positions on a mirror plane. The mol-ecular structure of the complex may be visualized as being built of [Mo(2)S(2)(µ-S)(2)(edt)(2)](2-) dianions and [Ag(2)(dppm)(2)](2+) dications connected by two Ag-µ-S(edt) and two Ag-µ(4)-S bonds.
ABSTRACT
In the title chain compound, [Ag(NO(3))(C(26)H(24)P(2))](n), the bis-(diphenyl-phosphino)ethane (dppe) units link the Ag(+) ions into chains along [001]. A nitrate anion is coordinated to the Ag atom. There is a centre of symmetry at the mid-point of the ethane C-C bond and a twofold rotation axis passes through the Ag, N and terminal O atoms. Each Ag atom is four-coordinated in a distorted tetra-hedral geometry by two O atoms of the nitrate anion and two P atoms of dppe ligands. The two aromatic rings are oriented at a dihedral angle of 73.77â (3)°.
