Strong Electronic Communication Research Articles

Isolation and Study of Ruthenium-Cobalt Oxo Cubanes Bearing a High-Valent, Terminal RuV-Oxo with Significant Oxyl Radical Character.

High-valent RuV-oxo intermediates have long been proposed in catalytic oxidation chemistry, but investigations into their electronic and chemical properties have been limited due to their reactive nature and rarity. The incorporation of Ru into the [Co3O4] subcluster via the single-step assembly reaction of CoII(OAc)2(H2O)4 (OAc = acetate), perruthenate (RuO4-), and pyridine (py) yielded an unprecedented Ru(O)Co3(μ3-O)4(OAc)4(py)3 cubane featuring an isolable, yet reactive, RuV-oxo moiety. EPR, ENDOR, and DFT studies reveal a valence-localized [RuV(S = 1/2)CoIII3(S = 0)O4] configuration and non-negligible covalency in the cubane core. Significant oxyl radical character in the RuV-oxo unit is experimentally demonstrated by radical coupling reactions between the oxo cubane and both 2,4,6-tri-tert-butylphenoxyl and trityl radicals. The oxo cubane oxidizes organic substrates and, notably, reacts with water to form an isolable μ-oxo bis-cubane complex [(py)3(OAc)4Co3(μ3-O)4Ru]-O-[RuCo3(μ3-O)4(OAc)4(py)3]. Redox activity of the RuV-oxo fragment is easily tuned by the electron-donating ability of the distal pyridyl ligand set at the Co sites demonstrating strong electronic communication throughout the entire cubane cluster. Natural bond orbital calculations reveal cooperative orbital interactions of the [Co3O4] unit in supporting the RuV-oxo moiety via a strong π-electron donation.

Quadrupolar Cyclopenta[hi]aceanthrylene-Based Electron Donor-Acceptor-Donor Conjugates: Charge Transfer versus Charge Separation.

Cyclopenta[hi]aceanthrylenes (CPAs) have been functionalized at two of the peripheral positions with electronically inert trimethylsilylethynyl (1), as well as with electron-donating 4-ethynyl-N,N-dimethylaniline (2), ethynyl ZnII phthalocyanine (3), and ethynyl ZnII porphyrin (4) units. Consistent with X-ray crystal structures of 2 and 4, analyses of absorption and fluorescence of 2-4 point to strong electronic communication between the CPA and the peripheral units, affording quadrupolar electron donor-acceptor-donor charge-transfer conjugates. By virtue of their quadrupolar/dipolar charge-transfer characters in the excited state, 2-4 exhibit fluoro-solvatochromism. Transient absorption spectroscopy confirmed delocalized quadrupolar ground states and formation of weakly solvent stabilized quadrupolar singlet excited states. The latter transform into strongly stabilized dipolar excited states before deactivating to the ground state in 2 and give rise to a fully charge separated state in 3 and 4.

Quadrupolar Cyclopenta[hi]aceanthrylene‐Based Electron Donor‐Acceptor‐Donor Conjugates: Charge Transfer versus Charge Separation

AbstractCyclopenta[hi]aceanthrylenes (CPAs) have been functionalized at two of the peripheral positions with electronically inert trimethylsilylethynyl (1), as well as with electron‐donating 4‐ethynyl‐N,N‐dimethylaniline (2), ethynyl ZnIIphthalocyanine (3), and ethynyl ZnIIporphyrin (4) units. Consistent with X‐ray crystal structures of 2 and 4, analyses of absorption and fluorescence of 2–4 point to strong electronic communication between the CPA and the peripheral units, affording quadrupolar electron donor‐acceptor‐donor charge‐transfer conjugates. By virtue of their quadrupolar/dipolar charge‐transfer characters in the excited state, 2–4 exhibit fluoro‐solvatochromism. Transient absorption spectroscopy confirmed delocalized quadrupolar ground states and formation of weakly solvent stabilized quadrupolar singlet excited states. The latter transform into strongly stabilized dipolar excited states before deactivating to the ground state in 2 and give rise to a fully charge separated state in 3 and 4.

Thermodynamic Hydricity of [FeFe]-Hydrogenases.

After remaining elusive for many years, terminal hydride states have now been identified in several native and mutant [FeFe]-hydrogenases. In this Perspective, hydride states of [FeFe]-hydrogenases are considered on the basis of hydricity, a thermodynamic parameter that has been instrumental for the rational design of synthetic molecular catalysts. Importantly, it is shown how the hydricity of [FeFe]-hydrogenases can inspire future research efforts in both the study of hydrogenases and the design of molecular catalysts. By using hydricity, quantitative linear free energy relationships can be developed to relate the driving force and rate of different [FeFe]-hydrogenase variants. Further development of these correlations across a wide range of hydrogenase variants can potentially lead to new insights into the structure-activity relationships of [FeFe]-hydrogenases. The hydricity of [FeFe]-hydrogenase is also compared to select transition metal hydride complexes, which emphasizes the strong electronic communication between the diiron active site and the extended protein scaffold of the enzyme. A mechanism is proposed for how key hydrogen bonding interactions might affect the hydricity of [FeFe]-hydrogenases, providing a basis for the emulation of these structural features in synthetic molecular complexes.

A new benzothienoindole-based bipolar host material for efficient green phosphorescent organic light-emitting diodes with extremely small efficiency roll-off

In this contribution, two new hole-transport units, 10 H -benzo[4,5]thieno[3,2- b ]indole (BTI) and 10 H -benzofuro[3,2- b ]indole (BFI), were developed to design and synthesize bipolar host materials namely 10-(3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-10 H -benzo[4,5]thieno[3,2- b ]indole.( mBTITrz ) and 10-(3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-10 H -benzofuro[3,2- b ]indole.( mBFITrz ), for phosphorescent organic light-emitting diodes (PHOLEDs). The effect of heteroatoms in the hole-transport unit on the physicochemical and electroluminescence properties of the hosts were investigated in detail. Interestingly, the phosphorescence of the compounds was highly dependent on the hole-transport unit, because it originated from their local excited state ( 3 LE), which was attributed to the interrupted strong electronic communication between donor and acceptor units by meta- mode of conjugation on the phenyl linker. Consequently, the mBTITrz showed high triplet energy ( E T ) of ∼2.88 eV compared to its counterpart mBFITrz ( E T ∼ 2.65 eV). Both compounds displayed marked thermal stability with high thermal decomposition temperatures of above 410 °C and glass-transition temperatures of above 103 °C. In addition, the single carrier device studies revealed a bipolar charge transporting character for the compounds. Furthermore, the compounds were evaluated as bipolar hosts for green PHOLEDs by employing Ir(ppy) 3 dopant. The mBTITrz- hosted device demonstrated much better performance than did the mBFITrz- hosted device, with a maximum external quantum efficiency of 21.3% and maximum current efficiency of 76.0 cd/A. Notably, the mBTITrz- based device exhibited excellent efficacy stability with uncompromised efficiency roll-off at 1000 cd/m 2 and an extremely low efficiency roll-off of 3.2% at 5000 cd/m 2 and 9.0% at 10,000 cd/m 2 . • Bipolar hosts with new hole transport units for high external quantum efficiency. • Small efficiency roll-off in green phosphorescent organic light-emitting diodes using the bipolar hosts. • Effect of heteroatom in the hole transport unit on the physical and device performances of the hosts.

Synthesis, Structure, Electrochemical, and Spectroscopic Properties of Hetero-Bimetallic Ru(II)/Fe(II)-Alkynyl Organometallic Complexes.

A series of heterobimetallic wire-like organometallic complexes [( tpy-C6H4-R)(PPh3)2Ru-C≡C-Fc]+ ( tpy-C6H4-R = 4'-(aryl)-2,2':6',2''-terpyridyl, Fc = [(η5-Cp)2Fe], R = -H, -Me, -F, -NMe2 in complexes 5-8, respectively) featuring ferrocenyl and 4'-(aryl)-2,2':6',2''-terpyridyl ruthenium(II) complexes as redox active metal termini, have been synthesized. Various spectroscopic tools, such as multinuclear NMR, IR spectra, HRMS, CHN analyses, and single crystal X-ray crystallography have been utilized to characterize the heterobimetallic complexes. The electrochemical and UV-vis-NIR spectroscopic studies have been investigated to evaluate the electronic delocalization across the molecular backbones of the Ru(II)-Fe(II) heterobinuclear organometallic dyads. Electrochemical studies reveal two well-separated reversible redox waves as a result of successive oxidation of the ferrocenyl and Ru(II) redox centers. The spin density distribution analyses reveal that the initial oxidation process is associated with the Fe(II)/Fe(III) couple followed by one electron oxidation of the ruthenium(II) center. The high Kc value (0.11-1.73 × 1012) and intense NIR absorption, with molar absorption coefficient (in the order of 103 M-1 cm-1) for the RuIIFeIII mixed-valence species, signify strong electronic communication between the two metal termini. The electronic coupling constant ( Hab) has been estimated to be 492 and 444 cm-1 for the structurally characterized complexes 6 and 7, respectively. The redox and NIR absorption features indicate that the mixed-valence system of the heterobinuclear dyads belongs to a Robin and Day "class II" system.

Stable Mixed-Valent Complexes Formed by Electron Delocalization Across Hydrogen Bonds of Pyrimidinone-Linked Metal Clusters.

Electron transfer across a mixed-valent hydrogen-bonded self-dimer of oxo-centered triruthenium clusters bridged by a pair of 4(3 H)-pyrimidinones is reported. Spectroelectrochemical studies in methylene chloride reveal that 1 rapidly self-dimerizes upon one-electron reduction, forming the strongly coupled mixed-valent hydrogen-bonded dimer (12)-. In the mixed-valent state, significantly broadened, partially coalesced ν(CO) bands are observed, allowing estimation of the electron transfer rate ( kET) by an optical Bloch line shape analysis. Simulation of the FTIR line shapes provides an estimate of kET on the order of 1011 s-1, indicating a highly delocalized electronic structure across the hydrogen bonds. These findings are supported by the determination of the formation constant ( KMV) for (12)-, which is found to be on the order of 106 M-1, or nearly 4 orders of magnitude higher than that for the neutral isovalent dimer (12). This represents a stabilization of approximately 5.7 kcal/mol (1980 cm-1) arising from electron exchange across the hydrogen bonds in the mixed-valent state. Significantly, an enormous intensity enhancement of the amide ν(NH) band (3300 cm-1) of (12)- is observed, supporting strong mixing of the bridging ligand vibrational modes with the electronic wave function of the mixed-valent state. These findings demonstrate strong donor-bridge-acceptor coupling and that highly delocalized electronic structures can be attained in hydrogen-bonded systems, which are often considered to be too weakly bound to support strong electronic communication.

Triphenylamine Functionalized Unsymmetrical Quinoxalines

AbstractA family of unsymmetrical quinoxalines 11–18 of types D‐A‐π‐D and D‐A‐A′‐D′ have been designed and synthesized by the Suzuki, Heck, Sonogashira, Ullmann coupling and [2+2] cycloaddition−retroelectrocyclic ring opening reactions. A systematic study was performed to explore the effect of donor, acceptor and π‐linker on the triphenylamine functionalized quinoxalines. The electronic absorption spectra of the ethynyl bridged quinoxaline 14 show red shifted absorption in the high‐energy region compared to quinoxaline 13. The quinoxalines 17 and 18 exhibit red shifted absorption in the near–infrared (NIR) region due to the incorporation of strong TCNE/TCNQ acceptor units. The TGA data reveals that triphenylethylene substituted quinoxaline 15 shows higher thermal stability compared to other quinoxalines. The electrochemical data exhibit strong electronic communication in quinoxalines 11–18. The incorporation of TCNE/TCNQ acceptor units results in greater stabilization of LUMO levels and low HOMO−LUMO energy gap in 17 and 18 which was supported by computational studies.

Supramolecular Hybrids of MoS2 and Graphene Nanosheets with Organic Chromophores for Optoelectronic Applications

A novel supramolecular strategy based on host–guest chemistry has been proposed for the noncovalent functionalization of MoS2 nanosheets with organic chromophores. Stable ternary complexes are formed between benzyl imidazole functionalized MoS2 and chromophores in the presence of cucurbit[8]uril host, resulting in noncovalent anchoring of donor and acceptor chromophores on the surface. On the other hand, in the case of graphene, we observe π–π stacking resulting in the face-on organization of chromophore on the surface. The MoS2 and graphene hybrids have been characterized by various spectroscopic techniques. The present design opens up new possibilities for the noncovalent functionalization of transition metal dichalcogenides even in the absence of delocalized π-electrons which are essential to alter their optoelectronic properties. In addition, these novel supramolecular hybrid materials with strong electronic communication between noncovalently anchored chromophores and the 2D nanosheets may find appli...

Core–shell porphyrin·multi-walled carbon nanotube hybrids linked by multiple hydrogen bonds: nanostructure and electronic communication

In this paper, multiple hydrogen bonding interaction of ureidopyrimidinone (UPM) was employed as the linking bridge for the formation of a novel porphyrin·multi-walled carbon nanotube (MWNT) hybrid, which was then used to fabricate a layer-by-layer (LbL) film composed of porphyrin-UPM·MWNT-UPM. Both in the assembled hybrid and the LbL film, porphyrin was closely attached to the surface of the MWNT under the strong multiple hydrogen bonding interaction, forming the core–shell structure. In addition, strong electronic communication was observed between porphyrin and MWNT. The hydrogen bonding association behavior between porphyrin-UPM and MWNT-UPM was attentively analyzed by UV–Vis spectra, fluorescent spectra and transmission electron microscope experiments. It was found that the hydrogen bonding interactions were crucial for the formation of the supramolecular hybrid and the LbL film as well as the occurrence of interfacial electronic communication. This result indicated that the introduction of strong noncovalent bonding interaction between donor and acceptor is an appropriate way to control the material structure and facilitate the interfacial electronic communication in the hybrids which lay the groundwork for their application in electrochemical sensors or photovoltaic devices.

A Manganese Nanosheet: New Cluster Topology and Catalysis.

While the coordination chemistry of monometallic complexes and the surface characteristics of larger metal particles are well understood, preparations of molecular metallic nanoclusters remain a great challenge. Discrete planar metal clusters constitute nanoscale snapshots of cluster growth but are especially rare owing to the strong preference for three‐dimensional structures and rapid aggregation or decomposition. A simple ligand‐exchange procedure has led to the formation of a novel heteroleptic Mn6 nanocluster that crystallized in an unprecedented flat‐chair topology and exhibited unique magnetic and catalytic properties. Magnetic susceptibility studies documented strong electronic communication between the manganese ions. Reductive activation of the molecular Mn6 cluster enabled catalytic hydrogenations of alkenes, alkynes, and imines.

A Manganese Nanosheet: New Cluster Topology and Catalysis

AbstractWhile the coordination chemistry of monometallic complexes and the surface characteristics of larger metal particles are well understood, preparations of molecular metallic nanoclusters remain a great challenge. Discrete planar metal clusters constitute nanoscale snapshots of cluster growth but are especially rare owing to the strong preference for three‐dimensional structures and rapid aggregation or decomposition. A simple ligand‐exchange procedure has led to the formation of a novel heteroleptic Mn6 nanocluster that crystallized in an unprecedented flat‐chair topology and exhibited unique magnetic and catalytic properties. Magnetic susceptibility studies documented strong electronic communication between the manganese ions. Reductive activation of the molecular Mn6 cluster enabled catalytic hydrogenations of alkenes, alkynes, and imines.

Interfacial Phenomenon and Nanostructural Enhancements in Palladium Loaded Lanthanum Hydroxide Nanorods for Heterogeneous Catalytic Applications

Hydrogenation and cross-coupling reactions are of great importance for industrial applications and noble metal based catalysts are filling the void since the last few decades. However, the high cost of noble metals and poor recycling performance provides an opportunity for chemists to look for alternate options. Herein, we present the use of Lanthanum hydroxide as support for loading ultra-low amount of Pd for hydrogenation and cross-coupling reactions. Lanthanum hydroxide having controlled morphologies comprises exposed crystallographic facets which interact with small sized Pd NPs and shows versatile and effective catalytic performance. The reduction of 4-NP over Pd/La(OH)3 was achieved within very short time (45s) with a rate constant of 60 × 10−3 s−1. The hydrogenation of styrene was also accomplished within 1 hour with much high TOF value (3260 h−1). Moreover, the Suzuki cross-couplings of iodobenzene and phenyl boronic acid into biphenyl completed within 35 min with a TOF value of 389 h−1. The strong interfacial electronic communication regulates electron density of catalytic sites and lowers energy for adsorption of reactant and subsequently conversion into products. Moreover, abundant hydroxyl groups on the surface of La(OH)3, large surface area, mono-dispersity and ultra-small size of Pd NPs also favors the efficient conversion of reactants.

Ferrocene-Alkynyl Conjugated Molecular Wires: Synthesis, Characterization, and Conductance Properties.

A novel series of 1,2,3-substituted ferrocene-based wires a1-a2 and b4-b5 have been synthesized by using an iterative Pd-mediated Sonogashira cross-coupling methodology. The molecular structures of a2 and b3 were determined by single-crystal X-ray analysis. Electrochemical data showed that there was a strong electronic communication among the ferrocenyl moieties in b1-b5. The UV absorption spectra indicated that replacing the 1,1'-substituted ferrocene unit with a 1,2,3-substituted ferrocene moiety causes delocalization of electrons in the extended π orbitals. The self-assembled monolayers of wire a1 and a2 on Au surfaces have been comprehensively characterized by electrochemistry and scanning tunneling microscopy break junction. The data demonstrated that 1,2,3-substituted ferrocene-based wires reduced the intermolecular π-π stacking, and furthermore solved the rotation problem in the 1,1'-substituted ferrocene-based wires.

Enhanced Hypsochromic Shifts, Quantum Yield, and π-π Interactions in a meso,β-Heteroaryl-Fused BODIPY.

We report the synthesis and investigation of an unprecedented 8-heteroaryl-fused BODIPY 4. This compound exhibits enhanced π-π stacking in the solid state, unusually large blue-shifts in the absorbance and emission spectra, and higher fluorescence quantum yield than its unfused precursor; DFT calculations suggest a small energy gap for 4 and strong electronic communication between the 8-OPh and the BODIPY core.

Heteroleptic Tetrapyrrole-Fused Dimeric and Trimeric Skeletons with Unusual Non-Frustrated Fluorescence.

Phthalocyanine (Pc) and porphyrin (Por) chromophores have been fused through the benzo[α]pyrazine moiety, resulting in unprecedented heteroleptic tetrapyrrole-fused dimers and trimers. The heteroleptic tetrapyrrole nature has been clearly revealed based on single-crystal X-ray diffraction analysis of the zinc dimer. Electrochemical analysis, theoretical calculations, and time-resolved spectroscopic results disclose that the two/three-tetrapyrrole-fused skeletons behave as one totally π-conjugated system as a result of the strong conjugative interaction between/among the tetrapyrrole chromophores. In particular, the effectively extended π-electron system through the fused-bridge induced strong electronic communication between the Pc and Por moieties and large transition dipole moments in the Pc-Por-fused systems, providing high fluorescence quantum yields (>0.13) and relatively long excited state lifetimes (>1.3 ns) in comparison with their homo-tetrapyrrole-fused analogues.

Effects of Strong Electronic Coupling in Chlorin and Bacteriochlorin Dyads.

Achieving tunable, intense near-infrared absorption in molecular architectures with properties suitable for solar light harvesting and biomedical studies is of fundamental interest. Herein, we report the photophysical, redox, and molecular-orbital characteristics of nine hydroporphyrin dyads and associated benchmark monomers that have been designed and synthesized to attain enhanced light harvesting. Each dyad contains two identical hydroporphyrins (chlorin or bacteriochlorin) connected by a linker (ethynyl or butadiynyl) at the macrocycle β-pyrrole (3- or 13-) or meso (15-) positions. The strong electronic communication between constituent chromophores is indicated by the doubling of prominent absorption features, split redox waves, and paired linear combinations of frontier molecular orbitals. Relative to the benchmarks, the chlorin dyads in toluene show substantial bathochromic shifts of the long-wavelength absorption band (17-31 nm), modestly reduced singlet excited-state lifetimes (τS = 3.6-6.2 ns vs 8.8-12.3 ns), and increased fluorescence quantum yields (Φf = 0.37-0.57 vs 0.34-0.39). The bacteriochlorin dyads in toluene show significant bathochromic shifts (25-57 nm) and modestly reduced τS (1.6-3.4 ns vs 3.5-5.3 ns) and Φf (0.09-0.19 vs 0.17-0.21) values. The τS and Φf values for the bacteriochlorin dyads are reduced substantially (up to ∼20-fold) in benzonitrile. The quenching is due primarily to the increased S1 → S0 internal conversion that is likely induced by increased contribution of charge-resonance configurations to the S1 excited state in the polar medium. The fundamental insights gained into the physicochemical properties of the strongly coupled hydroporphyrin dyads may aid their utilization in solar-energy conversion and photomedicine.

Synthesis and Photophysical Investigation of Tetraazaporphyrin Substituted with Aggregation‐Induced Emission (AIE) Active Moieties

AbstractThe synthesis and characterization of free‐base and ZnII tetraazaporphyrins with tetraphenylethylene (TPE) or diphenylphenanthrene (DPP) moieties that are known to be aggregation‐induced emission (AIE) active is reported. The optical spectra contain the characteristic Q and B absorption bands of Gouterman's four‐orbital model and a broad envelope of weaker charge‐transfer bands in the 450–600 nm region. The observed fluorescence emission lies beyond 670 nm and originates exclusively from the decay of the S1 state of the macrocycle, regardless of the excitation wavelength used. Theoretical calculations provide further evidence of strong electronic communication between the peripheral TPE or DPP moieties and the central ring. The ZnII complexes were found to have relatively high singlet‐oxygen quantum yields.

Push–Pull Porphyrin-Containing Polymers: Materials Exhibiting Ultrafast Near-IR Photophysics

Four push–pull polymers of structure (C≡C–[Zn]–C≡C–A)n (A = isoindigo (P1), bis(α-methylamino-1,4-benzene)quinone (P2), 2-(N-methylamino-1,4-benzene)-N-1,4-benzene-maleimide (P3), and 2,2′-anthraquinone (P4); [Zn] = [bis(meso-aryl)porphyrin]zinc(II) = donor) and models M1 and M2 (A′–C≡C–[Zn]–C≡C–A′; A′ = respectively naphtoquinone and 2-anthraquinone) were prepared and characterized (1H and 13C NMR, elemental analysis, GPC, TGA, cyclic voltammetry, steady state and ultrafast time-resolved UV–vis and emission spectroscopy) and studied by density functional theory (DFT) and time-dependent DFT (TDDFT) in order to address the nature of the low-lying singlet and triplet excited states. P1 (fully conjugated polymer), P2 (formally nonconjugated but exhibit strong electronic communication accross the chain) and P4 (formally nonconjugated but local conjugation between the donor and acceptor) are near-IR emitters (λmax > 750 nm). M1 and M2 are mono-C≡C–[Zn]–C≡C species, and P3 exhibits a very modest CT contribution...

Together Achieving More: Primary Care Team Communication and Alcohol-Related Healthcare Utilization and Costs.

Identifying and engaging excessive alcohol users in primary care may be an effective way to improve patient health outcomes, reduce alcohol-related acute care events, and lower costs. Little is known about what structures of primary care team communication are associated with alcohol-related patient outcomes. Using a sociometric survey of primary care clinic communication, this study evaluated the relation between team communication networks and alcohol-related utilization of care and costs. Between May 2013 and December 2013, a total of 155 healthcare employees at 6 primary care clinics participated in a survey on team communication. Three-level hierarchical modeling evaluated the link between connectedness within the care team and the number of alcohol-related emergency department visits, hospital days, and associated medical care costs in the past 12months for each team's primary care patient panel. Teams (n=31) whose registered nurses displayed more strong (at least daily) face-to-face ties and strong (at least daily) electronic communication ties had 10% fewer alcohol-related hospital days (rate ratio [RR]=0.90; 95% confidence interval [CI]: 0.84, 0.97). Furthermore, in an average team size of 19, each additional team member with strong interaction ties across the whole team was associated with $1,030 (95% CI: -$1,819, -$241) lower alcohol-related patient healthcare costs per 1,000 team patients in the past 12months. Conversely, teams whose primary care practitioner (PCP) had more strong face-to-face communication ties and more weak (weekly or several times a week) electronic communication ties had 12% more alcohol-related hospital days (RR=1.12; 95% CI: 1.03, 1.23) and $1,428 (95% CI: $378, $2,478) higher alcohol-related healthcare costs per 1,000 patients in the past 12months. The analyses controlled for patient age, gender, insurance, and comorbidity diagnoses. Excessive alcohol-using patients may fair better if cared for by teams whose face-to-face and electronic communication networks include more team members and whose communication to the PCP has been streamlined to fewer team members.