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1.
Dermatol Surg ; 46(12): 1705-1711, 2020 12.
Article in English | MEDLINE | ID: mdl-32852423

ABSTRACT

BACKGROUND: Follicular unit excision (FUE) is used to harvest follicular units for hair transplantation using trephine punches. The characteristics of FUE punches can impact the success of this technique; thus, many innovative punch designs and devices have been developed. With many options available, it can be difficult for the hair restoration surgeon to know which punch best suits the needs of their patients. OBJECTIVE: To provide a comprehensive review of punch shapes and devices available. METHODS: Search of PubMed, reference mining of relevant publications, and hand searching trade publications. RESULTS: We examined FUE punches and devices and consolidated descriptive information for each to create textual and visual guides. No single punch shape or device may suit all cases; thus, it is important to know the best uses and limitations of each. CONCLUSION: The surgeon should have a comprehensive knowledge base of available punch shapes and devices and understand the advantages and disadvantages of each. It is also beneficial to have an in-depth knowledge of skin properties and follicular unit structure. Ultimately, understanding the dynamics behind punch excision will enhance the FUE technique.


Subject(s)
Alopecia/surgery , Hair Follicle/transplantation , Tissue and Organ Harvesting/instrumentation , Equipment Design , Humans , Transplantation, Autologous/instrumentation
2.
J Cosmet Dermatol ; 19(8): 1883-1891, 2020 Aug.
Article in English | MEDLINE | ID: mdl-32445235

ABSTRACT

BACKGROUND: Early use of follicular unit excision (FUE) as a method of hair transplantation was limited by high rates of hair follicle transection. This hurdle has been overcome by innovative methods, punch shapes, and devices. With the vast array of tools available, it can be difficult for hair transplant surgeons to choose the best option for their practices. AIMS: To provide an in-depth review and comparison of currently available FUE methods, punch designs, and motorized devices, and discuss how these tools fit the unique skin and hair characteristics of patients. METHODS: A review of the literature and available information on FUE methods, punches, and devices, as well as the authors' experience in this area, is provided. RESULTS: Innovative FUE methods, punch shapes, and motorized devices have successfully minimized the rate of hair follicle transection. Methods include the use of sharp punches with depth control, and blunt rotating punches. Punch shapes such as flared, hybrid, and edge out have successfully reduced transections by keeping the cutting edge away from the follicles under the skin. The development of motorized devices using features including rotation, roto-oscillation, oscillation, vibration, suction, and hydration has also aided in achieving more successful graft excision. CONCLUSION: Follicular unit excision is a widely used technique by hair restoration surgeons. Therefore, it is important for physicians to be aware of the array of punches and devices available and understand how these tools can be used to adapt to the unique skin and hair characteristics of individual patients to optimize successful graft harvesting.


Subject(s)
Surgeons , Tissue and Organ Harvesting , Hair , Hair Follicle , Humans , Skin Transplantation
3.
Dermatol Surg ; 46(8): 1078-1083, 2020 08.
Article in English | MEDLINE | ID: mdl-32141930

ABSTRACT

BACKGROUND: Follicular unit excision (FUE) and follicular unit transplantation using strip surgery (FUT) are the dominant graft harvest methods in hair transplantation. The increase in the demand for FUE has reignited the debate of the relative superiority of the 2 methods. OBJECTIVE: To present a critical comparison of FUE and FUT graft harvesting techniques. MATERIALS AND METHODS: Search of PubMed, trade publications, and printed references. RESULTS: Follicular unit excision and FUT methods provide high-quality grafts, but differ in their scarring patterns of the donor region. Follicular unit transplantation results in a linear scar, whereas FUE produces punctate scars that are typically easily concealed. Distinct subgroups of hair transplant patients are eligible for FUE, FUT, or both procedures. CONLCUSION: Both FUE and FUT are equally effective in generating high-quality grafts. This detailed evaluation of the FUT and FUE procedures will assist hair restoration surgeons make informed decisions about the best approach for their patients.


Subject(s)
Hair Follicle/transplantation , Tissue and Organ Harvesting/methods , Cicatrix/etiology , Graft Survival , Humans , Patient Preference , Reoperation , Surgical Wound Dehiscence/etiology , Tissue and Organ Harvesting/adverse effects , Transplantation, Autologous/adverse effects , Transplantation, Autologous/methods
4.
Integr Environ Assess Manag ; 12(2): 264-72, 2016 Apr.
Article in English | MEDLINE | ID: mdl-26339869

ABSTRACT

As natural resources become increasingly limited, the value of restoring contaminated sites, both terrestrial and aquatic, becomes increasingly apparent. Traditionally, goals for remediation have been set before any consideration of goals for ecological restoration. The goals for remediation have focused on removing or limiting contamination whereas restoration goals have targeted the ultimate end use. Here, we present a framework for developing a comprehensive set of achievable goals for ecological restoration of contaminated sites to be used in concert with determining goals for remediation. This framework was developed during a Society of Environmental Toxicology and Chemistry (SETAC) and Society of Ecological Restoration (SER) cosponsored workshop that brought together experts from multiple countries. Although most members were from North America, this framework is designed for use internationally. We discuss the integration of establishing goals for both contaminant remediation and overall restoration, and the need to include both the restoration of ecological and socio-cultural-economic value in the context of contaminated sites. Although recognizing that in some countries there may be regulatory issues associated with contaminants and clean up, landscape setting and social drivers can inform the restoration goals. We provide a decision tree support tool to guide the establishment of restoration goals for contaminated ecosystems. The overall intent of this decision tree is to provide a framework for goal setting and to identify outcomes achievable given the contamination present at a site.


Subject(s)
Environmental Restoration and Remediation/methods , Goals , Conservation of Natural Resources , Ecosystem , Ecotoxicology , Environmental Monitoring
6.
Skinmed ; 12(4): 213-6, 2014.
Article in English | MEDLINE | ID: mdl-25335349

ABSTRACT

The number of surgical hair restorations performed worldwide is ever-increasing. Today's gold standard in surgical hair restoration is follicular unit transplantation (FUT). FUT refers to the transplantation of individual follicular units (FUs) from the donor region to the recipient region. Strip extraction and manual FU extraction (FUE) are the most common methods for FU production. While strip extraction and manual FUE both hold individual merits, they are also associated with a number of limitations. The introduction of a robotic surgical assistive device may circumvent many of the limitations associated with traditional strip and manual FUE methods. As with all new technologies, however, the robotic device will require further independently funded, peer-reviewed, clinical testing to establish its efficacy relative to existing hair restoration methods in clinical practice.


Subject(s)
Hair Follicle/transplantation , Hair/transplantation , Robotics , Humans , Minimally Invasive Surgical Procedures/instrumentation , Minimally Invasive Surgical Procedures/methods
7.
Facial Plast Surg Clin North Am ; 21(3): 375-84, 2013 Aug.
Article in English | MEDLINE | ID: mdl-24017979

ABSTRACT

The purpose of this article is to introduce the reader to the topic of follicular unit extraction (FUE) and to present an overview of the value of FUE to patients and physicians. In addition to this, the various methods and instrumentation for performing this method of graft harvest are discussed as well as some of the technique's inherent advantages and disadvantages. Topics unique to FUE, including body hair grafting, plug/minigrafts repair, and donor area management are addressed as well.


Subject(s)
Alopecia/surgery , Cosmetic Techniques , Dermatologic Surgical Procedures/methods , Hair Follicle/transplantation , Scalp/surgery , Tissue and Organ Harvesting/methods , Cosmetic Techniques/instrumentation , Dermatologic Surgical Procedures/instrumentation , Esthetics , Hair/transplantation , Humans , Patient Positioning , Postoperative Care , Robotics , Tissue and Organ Harvesting/instrumentation , Transplantation, Autologous/instrumentation , Transplantation, Autologous/methods , Treatment Outcome
8.
Aesthet Surg J ; 33(1): 128-51, 2013 Jan.
Article in English | MEDLINE | ID: mdl-23169821

ABSTRACT

Hair restoration is a highly sophisticated subspecialty that offers significant relief to patients with hair loss. An improved understanding of the aesthetics of hair loss and cosmetic hair restoration, hair anatomy and physiology, and the development of microvascular surgical instrumentation has revolutionized the approach to surgical hair restoration since the original description. Additional elements that contribute to the current state of the art in hair restoration include graft size, site creation, packing density, and medical control of hair loss. The results of hair restoration are natural in appearance and are provided with a very high level of patient satisfaction and safety. This aspect of cosmetic surgery is a very welcome addition to a traditional aesthetic practice and serves as a tremendous source for internal cross-referral. The future of hair restoration surgery is centered on minimal-incision surgery as well as cell-based therapies.


Subject(s)
Alopecia/surgery , Hair Follicle/transplantation , Plastic Surgery Procedures/methods , Adult , Female , Humans , Male , Middle Aged , Patient Safety , Plastic Surgery Procedures/adverse effects , Surgical Flaps
9.
J R Soc Interface ; 9(71): 1302-10, 2012 Jun 07.
Article in English | MEDLINE | ID: mdl-22158839

ABSTRACT

Soils are complex ecosystems and the pore-scale physical structure regulates key processes that support terrestrial life. These include maintaining an appropriate mixture of air and water in soil, nutrient cycling and carbon sequestration. There is evidence that this structure is not random, although the organizing mechanism is not known. Using X-ray microtomography and controlled microcosms, we provide evidence that organization of pore-scale structure arises spontaneously out of the interaction between microbial activity, particle aggregation and resource flows in soil. A simple computational model shows that these interactions give rise to self-organization involving both physical particles and microbes that gives soil unique material properties. The consequence of self-organization for the functioning of soil is determined using lattice Boltzmann simulation of fluid flow through the observed structures, and predicts that the resultant micro-structural changes can significantly increase hydraulic conductivity. Manipulation of the diversity of the microbial community reveals a link between the measured change in micro-porosity and the ratio of fungal to bacterial biomass. We suggest that this behaviour may play an important role in the way that soil responds to management and climatic change, but that this capacity for self-organization has limits.


Subject(s)
Bacterial Physiological Phenomena , Cell Communication , Ecosystem , Models, Biological , Soil Microbiology , Soil , Computer Simulation
10.
Inorg Chem ; 50(24): 12886-99, 2011 Dec 19.
Article in English | MEDLINE | ID: mdl-22077287

ABSTRACT

Nine nonlinear optical (NLO) chromophores with pyridinium electron acceptors have been synthesized by complexing new proligands with {Ru(II)(NH(3))(5)}(2+) electron-donor centers. The presence of long alkyl/fluoroalkyl chain substituents imparts amphiphilic properties, and these cationic complexes have been characterized as their PF(6)(-) salts by using various techniques including electronic absorption spectroscopy and cyclic voltammetry. Each complex shows three reversible/quasireversible redox processes; a Ru(III/II) oxidation and two ligand-based reductions. The energies of the intense visible d → π* metal-to-ligand charge-transfer (MLCT) absorptions correlate to some extent with the ligand reduction potentials. (1)H NMR spectroscopy also provides insights into the relative electron-withdrawing strengths of the new ligands. Single crystal X-ray structures have been determined for two of the proligand salts and one complex salt, [Ru(II)(NH(3))(5)(4-C(16)H(33)PhQ(+))]Cl(3)·3.25H(2)O (PhQ(+) = N-phenyl-4,4'-bipyridinium), showing centrosymmetric packing structures in each case. The PF(6)(-) analogue of the latter complex has been used to deposit reproducibly high-quality, multilayered Langmuir-Blodgett (LB) thin films. These films show a strong second harmonic generation (SHG) response from a 1064 nm laser; their MLCT absorbance increases linearly with the number of layers (N) and I(2ω)/I(ω)(2) (I(2ω) = intensity at 532 nm; I(ω) = intensity at 1064 nm) scales quadratically with N, consistent with homogeneous deposition. LB films on indium tin oxide (ITO)-coated glass show electrochemically induced switching of the SHG response, with a decrease in activity of about 50% on Ru(II) → Ru(III) oxidation. This effect is reversible, but reproducible over only a few cycles before the signal from the Ru(II) species diminishes. This work extrapolates our original solution studies (Coe, B. J. et al. Angew. Chem., Int. Ed.1999, 38, 366) to the first demonstration of redox-switching of NLO activity in a molecular material.


Subject(s)
Coordination Complexes/chemical synthesis , Ruthenium/chemistry , Surface-Active Agents/chemical synthesis , Coordination Complexes/analysis , Crystallography, X-Ray , Electrochemistry , Electrons , Ligands , Magnetic Resonance Spectroscopy , Models, Molecular , Molecular Structure , Optical Phenomena , Oxidation-Reduction , Salts/chemistry , Stereoisomerism , Surface-Active Agents/analysis
11.
J Clin Pharmacol ; 51(5): 695-705, 2011 May.
Article in English | MEDLINE | ID: mdl-20864621

ABSTRACT

Three phase 1 studies of eliglustat tartrate (Genz-112638), an oral inhibitor of glucosylceramide synthase under development for treating Gaucher disease type 1 (GD1), evaluated the safety, tolerability, and pharmacokinetics in healthy volunteers after escalating single doses (n = 99), escalating multiple doses (n = 36), and food (n = 24). Eliglustat tartrate was well tolerated at single doses ≤ 20 mg/kg and multiple doses ≤ 200 mg bid, with 50 mg bid producing plasma concentrations in the predicted therapeutic range. No serious adverse events occurred. Mild to moderate events of nausea, dizziness, and vomiting increased in frequency with escalating single and multiple doses. Single doses ≥ 10 mg/kg caused mild increases in electrocardiogram PR, QRS, and QT/QTc intervals. Single-dose pharmacokinetics showed dose linearity but not proportionality. Maximum plasma concentrations occurred at ~2 hours, followed by a monophasic decline with a ~6-hour terminal half-life. Unchanged drug in 8-hour urine collections was <1.5% of administered doses. Food did not significantly affect the rate or extent of absorption. Multiple-dose pharmacokinetics was nonlinear, showing higher than expected plasma drug concentrations. Steady state was reached ~60 hours after bid dosing. Higher drug exposure occurred in slower CYP2D6 metabolizers. Based on favorable results in healthy participants, a phase 2 trial of eliglustat tartrate was initiated in GD1 patients.


Subject(s)
Enzyme Inhibitors/pharmacokinetics , Food-Drug Interactions , Glucosyltransferases/antagonists & inhibitors , Pyrrolidines/pharmacokinetics , Administration, Oral , Adolescent , Adult , Biotransformation , Cytochrome P-450 CYP2D6/metabolism , Dizziness/chemically induced , Double-Blind Method , Drug Administration Schedule , Electrocardiography , Enzyme Inhibitors/administration & dosage , Enzyme Inhibitors/adverse effects , Enzyme Inhibitors/blood , Enzyme Inhibitors/urine , Female , Heart Rate/drug effects , Humans , Intestinal Absorption , Male , Models, Biological , Nausea/chemically induced , Pyrrolidines/administration & dosage , Pyrrolidines/adverse effects , Pyrrolidines/blood , Pyrrolidines/urine , Vomiting/chemically induced , Young Adult
12.
J Am Chem Soc ; 132(30): 10498-512, 2010 Aug 04.
Article in English | MEDLINE | ID: mdl-20617798

ABSTRACT

In this article, we present a detailed study of structure-activity relationships in diquaternized 2,2'-bipyridyl (diquat) derivatives. Sixteen new chromophores have been synthesized, with variations in the amino electron donor substituents, pi-conjugated bridge, and alkyl diquaternizing unit. Our aim is to combine very large, two-dimensional (2D) quadratic nonlinear optical (NLO) responses with reversible redox chemistry. The chromophores have been characterized as their PF(6)(-) salts by using various techniques including electronic absorption spectroscopy and cyclic voltammetry. Their visible absorption spectra are dominated by intense pi --> pi* intramolecular charge-transfer (ICT) bands, and all show two reversible diquat-based reductions. First hyperpolarizabilities beta have been measured by using hyper-Rayleigh scattering with an 800 nm laser, and Stark spectroscopy of the ICT bands affords estimated static first hyperpolarizabilities beta(0). The directly and indirectly derived beta values are large and increase with the extent of pi-conjugation and electron donor strength. Extending the quaternizing alkyl linkage always increases the ICT energy and decreases the E(1/2) values for diquat reduction, but a compensating increase in the ICT intensity prevents significant decreases in Stark-based beta(0) responses. Nine single-crystal X-ray structures have also been obtained. Time-dependent density functional theory clarifies the molecular electronic/optical properties, and finite field calculations agree with polarized HRS data in that the NLO responses of the disubstituted species are dominated by 'off-diagonal' beta(zyy) components. The most significant findings of these studies are: (i) beta(0) values as much as 6 times that of the chromophore in the technologically important material (E)-4'-(dimethylamino)-N-methyl-4-stilbazolium tosylate; (ii) reversible electrochemistry that offers potential for redox-switching of optical properties over multiple states; (iii) strongly 2D NLO responses that may be exploited for novel practical applications; (iv) a new polar material, suitable for bulk NLO behavior.


Subject(s)
2,2'-Dipyridyl/chemistry , Diquat/analogs & derivatives , Crystallography, X-Ray , Electrochemistry , Models, Molecular , Oxidation-Reduction , Spectrum Analysis
13.
Trends Ecol Evol ; 24(11): 599-605, 2009 Nov.
Article in English | MEDLINE | ID: mdl-19683830

ABSTRACT

Many ecosystems are rapidly being transformed into new, non-historical configurations owing to a variety of local and global changes. We discuss how new systems can arise in the face of primarily biotic change (extinction and/or invasion), primarily abiotic change (e.g. land use or climate change) and a combination of both. Some changes will result in hybrid systems retaining some original characteristics as well as novel elements, whereas larger changes will result in novel systems, which comprise different species, interactions and functions. We suggest that these novel systems will require significant revision of conservation and restoration norms and practices away from the traditional place-based focus on existing or historical assemblages.


Subject(s)
Conservation of Natural Resources/methods , Ecosystem , Climate Change , Environmental Monitoring , Human Activities , Humans , Models, Theoretical , Population Density
14.
Dermatol Surg ; 35(3): 425-7; discussion 427-8, 2009 Mar.
Article in English | MEDLINE | ID: mdl-19292834

ABSTRACT

BACKGROUND: Because hair restoration surgery has changed so significantly, the International Society of Hair Restoration Surgery (ISHRS) recently developed and published a Core Curriculum for Hair Restoration Surgery (CCHRS). The ISHRS organized a task force to develop training programs that would not only present the CCHRS but also provide the practical experience necessary to allow a physician to practice safe, aesthetically sound hair restoration surgery. The task force recognized early on that identification of core competencies for hair restoration surgeons was essential to guiding the development of these training experiences. This article presents the competencies that have been identified. OBJECTIVE: The intent of the Core Competencies for Hair Restoration Surgery is to outline the knowledge and skills that are essential to accurately diagnose and treat hair loss, to ensure patient safety, and to optimize aesthetic results. The ISHRS hopes that all existing surgery and dermatology training programs teaching hair restoration surgery procedures will find the Core Competencies useful in developing their curriculums. METHODS: The Core Competencies were developed through an organized review of the CCHRS by a team of experienced hair restoration surgeons and educators and reviewed and approved by the ISHRS Board of Governors. RESULTS: The diversity of these competencies demonstrate that contemporary hair restoration surgery is a specialty requiring knowledge of several medical disciplines, including genetics, endocrinology, dermatology, tissue preservation, and surgery. CONCLUSION: The International Society of Hair Restoration Surgery believes identification of these Core Competencies is an important contribution to physician education in hair restoration surgery, and physicians who demonstrate competency in these skills will satisfy patients with contemporary results in a safe environment.


Subject(s)
Clinical Competence/standards , General Surgery/standards , Hair/transplantation , Humans , Societies, Medical
15.
Facial Plast Surg ; 24(4): 404-13, 2008 Nov.
Article in English | MEDLINE | ID: mdl-19034817

ABSTRACT

Follicular unit extraction (FUE) is a method of producing follicular unit hair grafts that involves removing the grafts individually from the scalp. The advantages of this technique over the conventional strip harvest are that it does not leave a linear scar, and the procedure produces little or no postoperative pain and discomfort. There are some disadvantages such as increased surgical times, graft fragility, and higher cost to the patient. This article describes the instrumentation and surgical methodology of FUE. It also presents some surgical difficulties and how to minimize their impact. Indications and patient candidacy are also discussed.


Subject(s)
Alopecia/surgery , Hair Follicle/transplantation , Scalp/surgery , Skin Transplantation/methods , Tissue and Organ Harvesting/methods , Female , Humans , Male , Transplantation, Autologous
16.
JSLS ; 11(1): 66-71, 2007.
Article in English | MEDLINE | ID: mdl-17651559

ABSTRACT

BACKGROUND: Laparoscopic Nissen fundoplication (LNF) provides long-term improvement in the typical symptoms of gastroesophageal reflux disease. Few studies have prospectively addressed LNF in the community hospital or the effect of LNF on specific atypical symptoms, other related gastrointestinal symptoms, and weight change. METHODS: Data were collected prospectively on consecutive patients having LNF. Three typical, 6 atypical, and 3 other gastrointestinal symptoms were studied. RESULTS: Short-term data on 91 patients and long-term data on 84 patients were studied. Overall long-term improvement was 98%. Regarding typical symptoms, the greatest improvement occurred in heartburn and regurgitation. Regarding atypical symptoms, the greatest improvement occurred in cough and sore throat, but chest pain, hoarseness, and throat clearing also showed significant durable improvement. Bloating, nausea, and diarrhea showed no significant change from preoperative to postoperative surveys. Mild weight loss was common. CONCLUSION: LNF can be safely performed in a community hospital with results equal to those of university hospitals. Improvement in typical symptoms was greater than improvement in atypical symptoms, but results for both were significant and durable. Nonspecific gastrointestinal symptoms, such as nausea, bloating, and diarrhea, may be unrelated to Nissen fundoplication.


Subject(s)
Fundoplication , Gastroesophageal Reflux/surgery , Laparoscopy , Adolescent , Adult , Aged , Female , Gastroesophageal Reflux/diagnosis , Hospitals, Community , Humans , Male , Middle Aged , Postoperative Complications , Treatment Outcome
17.
J Phys Chem B ; 111(24): 6695-702, 2007 Jun 21.
Article in English | MEDLINE | ID: mdl-17402776

ABSTRACT

Electroabsorption (Stark) spectroscopy has been used to study the charge-transfer absorption from a transition-metal-cyanide complex to a TiO2 nanoparticle. Transition-metal cyanide/TiO2(particle) systems were synthesized using FeII(CN)(6)4-, RuII(CN)6(4-), MoIV(CN)(8)4-, and WIV(CN)8(4-). On formation of the M(CN)n4-/TiO2(particle) system, a new metal-to-particle charge-transfer (MPCT) absorption band is observed in the 390-480 nm region. Analysis of the absorption spectra suggests that the TiO2 level involved in the MPCT transition resides at significantly higher energy than the bottom of the conduction band and that the electronic coupling between the two metal centers is the dominant factor determining the position of the MPCT band maximum. The average charge-transfer distances determined by Stark spectra range from 4.1-4.7 A. The observation of relatively short charge-transfer distances leads to the conclusion that the MPCT absorption is from the transition-metal cyanide center to a level that is localized on the Ti atom bound to a nitrogen end of the [O2Ti-N-C-M(CN)x] system. The electronic coupling, Hab, calculated for a two state model is similar to values observed in dinuclear metal complexes.

18.
Inorg Chem ; 45(26): 11019-29, 2006 Dec 25.
Article in English | MEDLINE | ID: mdl-17173461

ABSTRACT

Four new complex salts trans[RuIICl(pdma)2LA][PF6]n [pdma = 1,2-phenylenebis(dimethylarsine); LA = 1,4-bis[E-2-(4-pyridyl)ethenyl]benzene (bpvb), n = 1, 1; LA = N-methyl-1,4-bis(E-2-(4-pyridyl)ethenyl)benzene (Mebpvb+), n = 2, 2; LA = N-phenyl-1,4-bis(E-2-(4-pyridyl)ethenyl)benzene (Phbpvb+), n = 2, 3; LA = N-(2-pyrimidyl)-1,4-bis(E-2-(4-pyridyl)ethenyl)benzene (Pymbpvb+), n = 2, 4] have been prepared. The electronic absorption spectra of 1-4 display intense, visible metal-to-ligand charge-transfer (MLCT) bands, with lambda(max) values in the range 432-474 nm in acetonitrile. Intense intraligand charge-transfer (ILCT) bands due to LA are also observed, with lambda(max) values in the range 350-416 nm. Cyclic voltammetric studies in acetonitrile reveal reversible RuIII/II waves with E(1/2) values of ca. 1.05 V vs Ag/AgCl, together with LA-based reduction processes that are irreversible with the exception of 1. Salts 1-4 have been investigated by using Stark (electroabsorption) spectroscopy in butyronitrile glasses at 77 K. These studies have afforded dipole moment changes, Deltamu12, for the MLCT and ILCT transitions which have been used to calculate molecular static first hyperpolarizabilities, Beta0, according to the two-state equation Beta0 = 3Deltamu12(mu12)2/(Emax)2 (mu12 = transition dipole moment, Emax = MLCT/ILCT energy). In contrast with related RuII ammine complexes, replacement of a central E-ethylene bond with a 1,4-phenylene unit does not appear to be an especially effective strategy for combating the NLO transparency-efficiency tradeoff in these pdma complexes. Single-crystal X-ray studies with the complex salts 2 and 3 and also with the pro-ligand salt [Phbpvb+] PF6.0.5HPF6 show that these materials all adopt centrosymmetric packing structures.

19.
J Am Chem Soc ; 128(37): 12192-204, 2006 Sep 20.
Article in English | MEDLINE | ID: mdl-16967970

ABSTRACT

In this article, we describe a series of complex salts in which electron-rich {Fe(II)(CN)(5)}(3)(-) centers are coordinated to pyridyl ligands with electron-accepting N-methyl/aryl-pyridinium substituents. These compounds have been characterized by using various techniques including electronic absorption spectroscopy and cyclic voltammetry. Molecular quadratic nonlinear optical (NLO) responses have been determined by using hyper-Rayleigh scattering (HRS) at 1064 nm, and also via Stark (electroabsorption) spectroscopic studies on the intense, visible d --> pi* metal-to-ligand charge-transfer (MLCT) bands. The relatively large static first hyperpolarizabilities, beta(0), increase markedly on moving from aqueous to methanol solutions, accompanied by large red-shifts in the MLCT transitions. Acidification of aqueous solutions allows reversible switching of the linear and NLO properties, as shown via both HRS and Stark experiments. Time-dependent density functional theory and finite field calculations using a polarizable continuum model yield relatively good agreement with the experimental results and confirm the large decrease in beta(0) on protonation. The Stark-derived beta(0) values are generally larger for related {Ru(II)(NH(3))(5)}(2+) complexes than for their {Fe(II)(CN)(5)}(3)(-) analogues, consistent with the HRS data in water. However, the HRS data in methanol show that the stronger solvatochromism of the Fe(II) complexes causes their NLO responses to surpass those of their Ru(II) counterparts upon changing the solvent medium.

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